Applies to all Barracuda Web Filters.
The Youtube.com website and Youtube videos are hosted on different domains. To allow these you will need to create a rule that allows access to both of these resources.
However, the media servers are on dynamic hostnames. A single hostname exception will fail. Instead a URL pattern is needed.
Place the following regular expression pattern in the Block / Accept > Url Patterns Allow list:
(ytimg.com youtube.com googlevideo.com gvt0.com gvt1.com gvt2.com)
This will allow both the website and the media servers.
Link to this page: