I think this might have to be the solution. Better to have to click the link to get to Reddit than having a thread full of videos playing audio.I wish there was something we can do about them but we can't. Only thing we can do is stop Reddit posts from posting and have to follow the link.
I found the setting, but the original posts were edited so now I can't test.You can disable auto play in your Reddit settings, so that might be it.