Hi (((((KJ)))))
This is probably not much help, but we don't think it is your computer.

We were chatting to a friend in England last night, at around the time you are talking about, and she was having the same problem. As she had played the first video several times before the problem started we considered it was unlikely to be a buffering issue, and more likely to be an issue with the you tube site. They have been busy wiping out heaps of videos that they have been ordered to delete for copyright reasons.

Has the problem cleared up now ? If it hasn't, post again & we will think about the kind of system you are running on the computer.