Go to Settings > Apps > YouTube and clear both cache and data to temporarily bypass the "update" prompt .

If the native app is broken, you can use these alternatives:

Videaura - Support the Vision. Unlock the Story.

App Youtube Android 5.1.1 -

Go to Settings > Apps > YouTube and clear both cache and data to temporarily bypass the "update" prompt .

If the native app is broken, you can use these alternatives: app youtube android 5.1.1