YTBetter - working 9/25/2021

// ==UserScript==
// @name        YTBetter
// @namespace   YTBetter
// @match       https://*.youtube.com/*
// @run-at      document-start
// @grant       none
// @version     1.1
// @author      トワ…
// @description Patches YouTube to bypass some limitations
// ==/UserScript==

(() => {
  const _DEBUG = false;
  const debug = (...msg) => {
    if(_DEBUG) {
      console.log("[YTBetter]", ...msg);
    }
  }

  const PatchPlayerResponse = (playerResponse) => {
    try {
      // Patch to allow DVR to work on all streams
      if(playerResponse.videoDetails) {
        playerResponse.videoDetails.isLiveDvrEnabled = true;
      }
    } catch (err) {
      debug("Failed to patch playerResponse", err);
    }
  };

  const GetPlayerResponse = (videoInfo) => {
    return videoInfo.raw_player_response || videoInfo.embedded_player_response || videoInfo.player_response;
  };

  const TrapVideoConstructor = (value) => new Proxy(value, {
    construct: (target, argumentsList, newTarget) => {
      debug("Trapped SE constructor with arguments", target, argumentsList, newTarget);

      (() => {
        if(argumentsList.length !== 2) {
          return;
        }

        let videoInfo = argumentsList[1];
        let playerResponse = GetPlayerResponse(videoInfo);
        if(typeof playerResponse === "undefined") {
          return;
        }

        if(typeof playerResponse === "string") {
          playerResponse = JSON.parse(playerResponse);
          delete videoInfo.player_response;
          delete videoInfo.embedded_player_response;
        }

        PatchPlayerResponse(playerResponse);
        if(playerResponse.videoFlags && !playerResponse.videoFlags.playableInEmbed) {
          try {
            // We need to patch these to force embeds to work
            //argumentsList[0].deviceParams.c = "WEB";
            for(const key in argumentsList[0]) {
              if(argumentsList[0][key] === "embedded") {
                debug("Patching embedded key", key);
                argumentsList[0][key] = "detailpage";
              }
            }
          } catch (err) {
            debug("Failed to patch embeds", err);
          }
        }
      })();

      return Reflect.construct(target, argumentsList, newTarget);
    },
  });

  const TrapNonembedVideoConstructor = (value) => new Proxy(value, {
    construct: (target, argumentsList, newTarget) => {
      debug("Trapped Nonembed constructor with arguments", target, argumentsList, newTarget);

      (() => {
        let player = argumentsList[8];
        player.allowLiveDvr = true
      })();

      return Reflect.construct(target, argumentsList, newTarget);
    },
  });

  const TrapCopyConf = (value) => new Proxy(value, {
    apply: (target, thisArg, argumentsList) => {
      if(argumentsList.length != 2) {
        return Reflect.apply(target, thisArg, argumentsList);
      }

      try {
        let client = argumentsList[1].c;
        let clientVer = argumentsList[1].cver;
        if(client === "WEB_EMBEDDED_PLAYER") {
          debug("Patching WEB_EMBEDDED_PLAYER");
          argumentsList[1].c = "WEB";
          argumentsList[0].el = "detailpage";
          if(!clientVer.includes(".")) {
            debug("Patching client version");
            argumentsList[1].cver = "2." + clientVer;
          }
        }
      } catch (err) {
        debug("CopyConf error", err);
      } finally {
        return Reflect.apply(target, thisArg, argumentsList);
      }
    },
  });

  const TrapConfigFetch = (value) => new Proxy(value, {
    apply: (target, thisArg, argumentsList) => {
      if(argumentsList.length == 0) {
        return Reflect.apply(target, thisArg, argumentsList);
      }

      let key = argumentsList[0];
      let result = Reflect.apply(target, thisArg, argumentsList);
      //debug(key, result);
      switch (key) {
        case "INNERTUBE_CONTEXT":
          try {
            let client = result.client.clientName;
            let clientVer = result.client.clientVersion;

            if(client === "WEB_EMBEDDED_PLAYER") {
              result.client.clientName = "WEB";
              if(!clientVer.includes(".")) {
                debug("Patching client version");
                result.client.clientVersion = "2." + clientVer;
              }
            }
          } catch (err) {
            debug("ConfigFetch error", err);
          } finally {
            return result;
          }
          //case "INNERTUBE_CONTEXT_CLIENT_NAME":
          //  if (result === 56) {
          //    // YouTube uses this header to determine if you're watching from an embedded video player,
          //    // we have to strip it to force embeds to work even when they're disabled by the author.
          //    debug("Stripping INNERTUBE_CONTEXT_CLIENT_NAME");
          //    return;
          //  }
          //  break;
      }

      return result;
    },
  });

  const TrapUpdateVideoInfo = (value) => new Proxy(value, {
    apply: (target, thisArg, argumentsList) => {
      (() => {
        if(argumentsList.length !== 3) {
          return;
        }

        let videoInfo = argumentsList[1];
        let playerResponse = GetPlayerResponse(videoInfo);
        if(typeof playerResponse === "undefined") {
          return;
        }

        if(typeof playerResponse === "string") {
          playerResponse = JSON.parse(playerResponse);
          delete videoInfo.player_response;
          delete videoInfo.embedded_player_response;
        }

        PatchPlayerResponse(playerResponse);
      })();
      debug("TrapUpdateVideoInfo", thisArg, argumentsList);
      return Reflect.apply(target, thisArg, argumentsList);
    },
  });

  const TrapYTPlayer = (value) => {
    const VideoConstructorFuncRegex = /this.allowLiveDvr=this./;
    const VideoNonembedConstructorFuncRegex = /function\(a,b,c,d,e,f,h,l,m,n\){m=void/;
    const ConfigFetchFuncRegex = /^function\(a,b\)\{return a in /;
    const CopyConfFuncRegex = /^function\(a,b\)\{for\(var c in b\)a\[c\]=b\[c\]\}$/;
    const UpdateVideoInfoRegex = /a.errorCode=null/;

    let FoundVideoConstructor = false;
    let FoundNonembedVideoConstructor = false;
    let FoundConfigFetch = false;
    let FoundCopyConf = false;
    let FoundUpdateVideoInfo = false;

    return new Proxy(value, {
      defineProperty: (target, property, descriptor) => {
        (() => {
          if(typeof descriptor.value !== "function") {
            return;
          }
          if(!FoundUpdateVideoInfo) {
            if(UpdateVideoInfoRegex.test(descriptor.value.toString())) {
              // UpdateVideoInfo is used for embeded videos, we need to trap
              // it to enable DVR on embeds.
              debug("Found UpdateVideoInfo func", property, descriptor.value);
              descriptor.value = TrapUpdateVideoInfo(descriptor.value);
              FoundUpdateVideoInfo = true;
              return;
            }
          }

          if(!FoundCopyConf) {
            if(CopyConfFuncRegex.test(descriptor.value.toString())) {
              // CopyConfFunc is used to copy configuration data between objects,
              // we patch it and change some data as it's copied
              debug("Found CopyConf func", property, descriptor.value);
              descriptor.value = TrapCopyConf(descriptor.value);
              FoundCopyConf = true;
              return;
            }
          }

          if(!FoundVideoConstructor) {
            if(VideoConstructorFuncRegex.test(descriptor.value.toString())) {
              // VideoConstructor func is the constructor for videos,
              // we use it to patch some data when new videos are loaded.
              debug("Found VideoConstructor func", property, descriptor.value);
              descriptor.value = TrapVideoConstructor(descriptor.value);
              FoundVideoConstructor = true;
              return;
            }
          }

          if(!FoundNonembedVideoConstructor) {
            if(VideoNonembedConstructorFuncRegex.test(descriptor.value.toString())) {
              // VideoConstructor func is the constructor for videos,
              // we use it to patch some data when new videos are loaded.
              debug("Found NonembedVideoConstructor func", property, descriptor.value);
              descriptor.value = TrapNonembedVideoConstructor(descriptor.value);
              FoundNonembedVideoConstructor = true;
              return;
            }
          }

          if(!FoundConfigFetch) {
            if(ConfigFetchFuncRegex.test(descriptor.value.toString())) {
              // ConfigFetch func is used to fetch configuration data used in HTTP headers,
              // we need to strip some of them to force embeds to work.
              debug("Found ConfigFetch func", property, descriptor);
              descriptor.value = TrapConfigFetch(descriptor.value);
              FoundConfigFetch = true;
              return;
            }
          }
        })();

        return Reflect.defineProperty(target, property, descriptor);
      },
    });
  }

  Object.defineProperty(window, "_yt_player", {
    value: TrapYTPlayer({}),
  });
})();