>>289073713
If you must have embedding, 4chanx has a pretty short list of supported sites https://github.com/ccd0/4chan-x/blob/63d62c233d84f97412b50e8b3c50c4bb081246ad/src/Linkification/Embedding.coffee#L264
Otherwise you can just upload mp4s to catbox.moe and it'll play fine in your browser.