Please support animated gif if not video.
I know video might be asking for a lot (even if it is a short video), but I think supporting animated gifs in addition to regular images in the margins is very feasible. Especially because there are many free services to convert video files to gifs online.

For example, I’m reading a book on horses I’d like to share. It would be useful to provide gifs tather than static I ages to illustrate the different gaits mentioned in the book.
https://commons.m.wikimedia.org/wiki/File:Muybridge_horse_gallop_animated_2.gif