The ProxySG or Advanced Secure Gateway (ASG) allow or block access to YouTube videos based on their category using Visual Policy Manager (VPM) or Content Policy Language (CPL).
SGOS 126.96.36.199 introduced the ability to categorize YouTube videos.
When enabled, the various YouTube categories can be selected within Visual Policy Manager.
Additionally, you can use CPL. For example:
See also How to identify Blue Coat categories for YouTube in the access log for information on how these categories are written to the Access Logs.