Edit: I finally found a solution. Even though the problem still exists in Firefox, it can still be played if you tap on it once or twice ans the video plays despite the error. This also fixed YouTube app's playback problem etc (cannot be played, please try again later) Videos are instantly played after fix. Here's what you have to try; 1- Go into settings in your phone. 2- Scroll down until you see 'About Phone' option and tap on it. 3- Scroll down and you should see 'Build number. Tap on it few times until 'Developer Options' is enabled. 4- Go back into Settings and you should now see the 'Developer Options' in the menu. Tap on it. 5- Scroll down until you get to the section where it says Media. On my phone the option is given as; "Use AwesomePlayer (deprecated)" I turned on that option and restarted my phone and all my playback issues with video playback was fixed completely. However; Firefox is still persistent with the error messages, especially on YouTube. I still get the "format and mime type" error message displayed but once I tap on it once, the error disappears and the video plays nice and fast. I think developers should check it out, during my research on couple of forums, I noticed many people are having the same problem. All the best.