Youtube would not let me watch any videos... "An error occurred. Please try again later." was displayed on every video.
After a lot of searching, and failed suggestions from other users, I found the solution:
> You need to delete all youtube rules in your ad blocking software, such as Adblock Plus. You should now be able to view videos again. If you like, disable your ad blocker to test this solution before you delete any youtube rules.
Apparently Google doesn't want people circumventing their ads on youtube... As such, they offer absolutely no help in their tech support forum for this issue.
Hope that helps anyone with this issue!