Hi

Is this just with YouTube videos?

No this all videos from any website

Do you have an example of a video where this happens?

any and every website I go to. MSN.com is my start page, any video there will start playing. Yahoo.com same. MLB.com. Any website with a video on it, the video start playing

Hi

Are you able to share a screenshot of your Autoplay settings in Firefox for Android in a reply to this thread?

Do you have an example of a video where this happens?