I have recently purchased Mibox 3. I keep getting message "Unfortunately, YouTube has stopped" even in cases when I didn't open the app as well as it stops playing in the background like any other video service, obviously, . I have noticed this when I update the app as the previous version is working well. I have tried a factory reset several times as well as clearing cache and data. Any suggestion to fix this issue? Could it be a hardware issue?
Have you disabled any pre-installed apps?
I don't use Google Movies, Google Games, etc so I started disabling those services. When I disabled Google App it caused a lot of issues with the home page. I believe that is also tied to the YouTube app now.
Enable any disabled (not uninstalled) apps one at a time, starting with the Google App. One at a time for trial and error.
If you haven't disabled any, clear Google App's cache/data and Google Play's as well.
Do you own a Chinese or international MiBox3?
I had simular problems when I used the Chinese ROM, after I changed this to the international ROM everything looks ok.
I had the same issue on my Mibox last week, it stopped after I cleared the cache and data and left the app closed after a reboot so it doesn't show in Active Apps anymore. I use an app called Smart Youtube TV as my standard YT app, so that's the only suggestion I could give you :(