I was wondering about this. Sorry.
I think there is a video option in settings about video playback, you can set to wifi. Not sure if this will helps with data tho. 🤔
Discussion
Yes this seems to fix this problem when on data
Settings > 
OK, thanks! That helps stop them from automatically playing, but what if I want to watch in ULTRA LOW DEFINITION (144p)? I'm trying to go the opposite direction on technology... Simpler is better...
Ah, I don't know about any settings like this. But it's a good idea for a setting. ¯\_(ツ)_/¯