Generate thumbnails for videos and expose them via opengraph media tags

[Hubro]

Hey Hubro, a buddy of mine and I forked Clipface to mess around with it a bit to have some fun, but one of the things we did was test max's theory about the og:image. Turns out max is correct. I tested a 150MB clip and it didn't load, then we just forced every video to use the same test image and restarted clipface with that change. Then, the embed instantly loaded, but with the placeholder image there and now the 150MB file plays in Discord embedded.

Here is the commit on our fork where we made that change

Interesting! So I guess the reason Discord downloads the video is in order to generate a thumbnail image.

I guess I have to add thumbnail generation 😄

Originally posted by @Hubro in #20 (comment)