https://twitter.com/MrAndyNgo/status/1304206833209417728
Any number of programs or sites or browser plugins out there that can convert videos from YT or other social media to mp4. Just search for youtube converter and pick one. I didn't do that one, but if I needed to I would take the youtube URL and add pp before the .com
So for example for a video with a URL of
https://www.youtube.com/watch?v=IjjhBhBouTI
You could change it to https://www.youtubepp.com/watch?v=IjjhBhBouTI and it provides you a download link.
For Twitter videos I use these: http://twittervideodownloader.com/
or
https://www.savetweetvid.com/