The post you showed in the screenshot does look fine to me both in classic and compact view on an instance with latest.
But I'd agree not all of your concerns have been addressed. I don't believe redgifs work (well), so will try to look into that if possible, but might be out of my depth.
The playback continuing is interesting. I had made a change long ago to not download every time it was expanded / collapsed as before it would make a request every single time, instead I changed it to just hide and show it after the first load, so that sounds like a side effect of that. Perhaps there's some way for me to also indicate to pause media, I will check