Try one of these articles:
- Add-on signing in Firefox for Android You'll see a warning in Firefox for Android when you try to install unverified or unsigned add-ons. Learn more about add-on signing.
- Firefox for Android displays blank web pages If you see blank web pages or a white screen when you open Firefox on your Android device, try these steps to fix the problem.
- I can't play videos or audio on Firefox for Android 5.0 (Lollipop) If you're using Firefox on your Nexus 6 or Nexus 9, you might experience temporary issues with video and audio files. Learn how to fix them.
- Some videos won't play in background Some popular video websites have changed their settings on the server side so that videos will no longer play in the background.