1. Download youtube-dl.exe and put it in a folder somewhere https://youtube-dl.org
2. Right click inside that folder while holding shift. Click "Open Powershell window here."
3. In Firefox or Chrome, open the video page and push F12 before the video starts playing. A toolbox will open. Go to the Network tab of the toolbox. Find the first .m3u8 file in the list of requests, right click it and copy URL.
4. Click the m3u8 URL in the toolbox to show the request headers on the right. Copy the cookie (beginning with Cookie: )

ILLUSTRATION: https://i.imgur.com/oRb6f0k.png

Now, put the m3u8 URL and the cookie together in a command like this.

youtube-dl https://vod2.spwn.jp/whatever.m3u8 --add-header "Cookie: CloudFront-Key-Pair-Id=LOTSOFJUNKHERE"

Copy this into the powershell window and hope it works