Seems to work?!

-- BizHawk Hexing thingy?

dofile("tablehandling.lua")

oldrecord = {}
newrecord = {}

function nothingpressed()
   local k = joypad.get(1)
   return not(k.left or k.right or k.up or k.down or k.A or k.B or k.X or k.Y or k.L or k.R or k.start or k.select)
end

mode = "recording"

--ENTER BIG OFFSETS MANUALLY HERE--
offset = 0
--ENTER BIG OFFSETS MANUALLY HERE--

while(true) do
   emu.frameadvance()
   keys = input.get()
   if keys["R"] == true then
      mode = "replay"
   end
   if keys["F11"] then
      table.save(oldrecord,"recorded.txt")
      gui.text(0,100,"current record saved to recorded.txt")
   end
   if keys["F12"] then
      oldrecord = table.load("recorded.txt")
      gui.text(0,105,"loaded record from recorded.txt")
   end
   --note: you will see the offset change one
   --frame later than you expect.
   if keys["numpad+"] then
      offset = offset + 1
   end
   if keys["numpad-"] then
      offset = offset - 1
   end
   if keys["numpad0"] then
      offset = 0
   end
   -- "recording" mode records controller data (for first controller)
   if mode == "recording" then
      gui.text(180,20,"offset: " .. tostring(offset))
      gui.text(180,0,"recording, press R to switch")
      cf = emu.framecount()

         if oldrecord[cf] == nil then
            oldrecord[cf] = {}
         end
       oldrecord[cf] = joypad.get(1)
   end
   -- "replay" mode does the following:
   -- _if the emulator is in "rerecording" mode, it will input
   --   the previously recorded keys
   -- _you can specify an offset for that by pressing
   --   numpad+, numpad-, or numpad0_
   --   or you can override it by entering some new input.
   -- _if you want no input in the next frame,
   --   use numpad*
   if mode == "replay" then
      gui.text(180,0,"replay mode (old minus new)")
      cf = emu.framecount()
      newrecord[cf] = {}
      gui.text(180,20,"offset: " .. tostring(offset))
      keys = input.get()
      if oldrecord[cf+offset] ~= nil and oldrecord[cf+offset] ~= nil then
         if nothingpressed() and not keys["numpad*"] then
            joypad.set(oldrecord[cf+offset], 1)
            gui.text(0, 0, "RECORDED input used from frame " .. tostring(cf+offset))
         else
            gui.text(0, 0, "MANUAL input used")
         end
      else
         gui.text(0,0,"no controller data available")
      end
   end
end