Jischinger has identified one way of watching blocked YouTube videos (assuming they block only the standard URL). This may not work for everyone, and your last resort is a free “virtual tunnel.” I have used vtunnel before but it requires a major virus wipe after a few sessions. It’s not a safe way to surf.
To watch blocked YouTube videos, simply grab the alpha numeric code from the URL (starting after the = sign) and paste it after this URL: http://www.youtube.com/v/.
Got it? It gives you a full screen image. Example: