In the following picture you can see what happens when I try to play videos in Youtube only: Picture of playing Youtube Video
Other apps work just fine, I've tried Netflix and Redbull TV, but I use Youtube a lot.
Does anyone have an idea on how to solve this issue?
YouTube on my Mi Box 3 works fine, so I would recommend deleting and then reinstalling the app, then rebooting the Mi Box, just for good measure.
Actually, you could try rebooting first, then if YouTube still doesn't work then go to the uninstall/reinstall and reboot thing.
That's my usual go to when crap happens with an Android app, the good/great news is that the uninstall/reinstall process is easy and pretty painless.
Hope this helps.
Good luck!
Go to app settings select YouTube then delete the app cache and delete app data too. That should work
Disable it and install Smart YouTube