Cool - Glad it solved yours as well.
It was somewhat odd at YouTube - where video loaded was just a black screen - no further action.
Then select random videos in menu - some of them did play. Even ones played Ok in my feed that I loaded.
If one did not play as to why you were there - non of the videos of that member played.
It really threw me for a loop what the cause was. Glad I held off with the screwdriver.