Completely off topic but this website is how it should be done. No JavaScript enabled and I can play the videos and see the text and images. Well done.
https://sachachua.com/blog/2024/01/2024-01-28-yay-emacs-clos...
Which video codec? Originally webm could contain only VP8, but nowadays it can also contain VP9 and AV1. It's possible that Apple only implemented VP8 (https://caniuse.com/webm implies that it has implemented VP8 and VP9 but has VP9 disabled by default); if this video uses a newer codec, it won't work.