Ive said it before on GitHub, I dont think `TVHTML5_SIMPLY_EMBEDDED_PLAYER` is the great solution everyone thinks it is. Yeah, you can get the age-restricted videos anonymously. However you can also get those videos by logging in, which the author doesn't mention:

    POST /youtubei/v1/player HTTP/1.1
    Host: www.youtube.com
    Authorization: Bearer ya29.a0AVvZVsqRwNWFI3R0MSxnugyNlxbqIOXcwXkeA6NMOcpv_...
    
    {
     "contentCheckOk": true,
     "context": {
      "client": {
       "clientName": "ANDROID",
       "clientVersion": "18.04.35"
      }
     },
     "racyCheckOk": true,
     "videoId": "Cr381pDsSsA"
    }

and `TVHTML5_SIMPLY_EMBEDDED_PLAYER` comes with strong drawbacks. Some videos under that client require a JavaScript signature for BOTH downloading and unthrottling. Each person is welcome to their own opinion, but I just dont think its worth the complexity of parsing some arbitrary JavaScript with Python when you can just log in (programmatically as above). Personally I use the ANDROID client, which avoids all JavaScript signatures. Also not mentioned in the article is that you can actually take the throttled URLs as is, and download pieces concurrently for a pretty good result. So each piece is still downloading slowly, but if you use on the order of 99 connections, you get decent speed. You would think you get IP blocked or something for this, but I downloaded quite a bit using this method as a test and the YouTube server allowed it. The combined resultant speed was only something like 2 Mbps, so big picture it doesn't seem like an abuse. My YouTube OAuth code is here for any interested:

http://2a.pages.dev/mech