Also as an actual answer I couldn’t peg a decade or year because it sounds like every MIDI file ever played on a Pirated video game installation.

To embed a webm or mp4 file you do it the same way you would embed an image. ![](https://files.catbox.moe/klildh.mp4) is the code for this embedded video, for example. So, ![](http://myurl/to/my/file.mp4) or something like that. It does not work on all mobile apps for Lemmy, most notably Jerboa breaks the embed.