You just put the regular link between the youtube tags. The BBcode does the rest.
If it's a DNS ban, use these IPs.
youtube.com. 300 IN A 74.125.227.134
youtube.com. 300 IN A 74.125.227.129
youtube.com. 300 IN A 74.125.227.137
youtube.com. 300 IN A 74.125.227.132
youtube.com. 300 IN A 74.125.227.142
youtube.com. 300 IN A 74.125.227.131
youtube.com. 300 IN A 74.125.227.130
youtube.com. 300 IN A 74.125.227.128
youtube.com. 300 IN A 74.125.227.135
youtube.com. 300 IN A 74.125.227.136
youtube.com. 300 IN A 74.125.227.133
IE
http://74.125.227.134Or you can also change your DNS to these name servers from opendns.org
nameserver 208.67.222.222
nameserver 208.67.220.220
If it's IP based, the easiest way is to browse through an open proxy server. That, by the way, is how you can view content that is blocked in your country due to lack of copyright agreement. You just go through a proxy from a country that does have a copyright agreement.