In the Facebook app on Android, videos starts playing automatically, both on Wi-Fi and Cellular. But you can do as follows to disable Facebook autoplay on Android:
1. Open Facebook application on your Android phone or tablet
2. Go to the last tab (the three line icon)
3. Scroll down and under the "Help & Settings", tap the App Settings option
4. Now under the "General Settings", tap the Video Auto-play option
5. Select "Off" to competently disable the Auto-play feature on Facebook for Android, Select "On" to enable the feature, or select "Wi-fi only" to enable autoplay feature only on Wi-Fi and disable it when using the SIM data.