Videos should never play automatically, especially when I have not gotten to that feed yet because I have not scrolled down far enough. If/when the video to play, I will click the play button myself.
Gifs are fine playing automatically because they don’t have sound and usually have short loops.
My response:
I just upgraded my feed parser and it now handles embeds far better than before. So what was happening was that parts of the embed were being mangled before, whereas now they work fine.