don't require HLS playback: mp4 for all videos

Similar issues: #263, #464

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Would be nice to be able to get MP4 format for all videos. When you go through the Real™ Twitter API, you can get the MP4 link for any video, not sure if you can through however Nitter is doing the scraping. Example:

• nitter link: https://nitter.net/sahilkapur/status/1527092111195226114
• twitter link: https://twitter.com/sahilkapur/status/1527092111195226114
• direct mp4: https://video.twimg.com/ext_tw_video/1527078073073651712/pu/vid/1280x592/co45-zhhUMy1vBC1.mp4?tag=12

For nitter, you end up with a plethora of .m3u8 and .m4s URLs after HLS playback is enabled. You cannot play any non-GIF videos without HLS playback enabled.

[zedeus]

This is implemented and (almost) fully working, but requires an implementation of video streaming I haven't gotten flawless yet due to a weird quirk with how Twitter's CDN/cache works. I want to look into it again soon, I made the implementation about two years ago.

I look forward to it. \o/

[ericpa06]

This would be only thing remaining to make Nitter perfect 👌 Hope you guys are able to implement it soon.

[zedeus]

It's implemented here #634 but needs more testing since Twitter's mp4 streams seemingly aren't meant to be streamed. Weird handling of cache misses is necessary by retrying requests for up to several seconds.