All videos are corrupted since Firefox 53 with my Galaxy S4, model number GT-I9515, Android 4.4.2. This is the same problem as described here: https://support.mozilla.org/en-US/questions/1158437 I'm sure this is bug 1360626 – so please handle it like the S3 in your next builds. (I have opened a new thread, because kbrosnan has asked for a specific model number for the S4.) Thank you.