I was able to reproduce your problem... I did play theatvideo from TER (you posted a day ago, I believe).
Just now, I went directly to YouTube, searched for the same video (it has Linda's face on it) and tried to play it:
1) Use Safari - OK, plays without problem
2) Use Firefox - NOK, I get the same error message.
Did a quick Web search using "An error has occurred, try again later" and sure enough there are several posts that point to the Shockwave Flash player being at fault. I tried one suggestion - disable Shockwave and then re-enable it. This works for me, but not permanently (after a couple of plays, the error re-occurs).
Other posts suggest adding the HTML5 player - it supposedly does not have the problem:
https://addons.mozilla.org/en-US/firefox/addon/youtube-all-html5/
I just tried it and it appears to work.
Hopes this helps...