This is 570k and runs in a webassembly runtime:
https://archive.org/details/flash_badger
SVG could do that too. Minimal javascript plus audio tags.
http://xn--dahlstrm-t4a.net/svg/audio/html5-audio-in-svg.svg
yes stuff like that & the IOSYS MVs. you technically can do stuff like that today theres nothing stopping you from doing it with svgs but i meant more the social part of it. its just interesting that if you want to do the same thing (put an animated video on the inernet) the usual way its now 10x bigger yet looks worse.
also i dont think theres anything like Flash (the authoring software) but for SVGs. i hope there is one but for now I wouldnt say inkscape + a text editor counts