For those of you that use Facebook on your iPhone, and don’t have an unlimited data plan, you’ll want to do the below:
Click on Settings, and scroll down until you see Facebook. Then click on it, and goto Settings. You should then see an area for Video settings. Click the slider next to turn on Auto-play on WiFi Only. This will stop videos from Auto-playing in your News Feed if you’re using your cell phones data.
If you’re an Android user, you should have the same setting.