Just out of curiosity. Did you guys go into red pill mode and install dependencies?
Version 7 loads and plays everything I select. Their might be other dependencies or apps that are blocking Mtube from working. One of the biggest blocks for me was Gnumeric it has a python issue that prevented me from loading other apps properly. The minute I removed it every app since has loaded and worked perfectly. Just a suggestion, no offense to Gnumeric developer. Dan