If you wanna save your data & have headache when you open your facebook and videos will auto play then no need to worry just follow bellow steps & also you can watch below video to stop auto-play videos on your facebook account
1. Goto your facebook settings
2. Then click on video
3. Now in the option of Auto-Play Videos select off
thats it... now on your facebook account will not be play auto videos.
I hope you like this trick feel free to comment.