Restricting access to YouTube (replacement for the YouTube Education filter feature) (378277)
Previous versions of FortiOS supported YouTube for Schools (YTfS). As of July 1, 2016 this feature is no longer supported by YouTube. Instead you can use the information in the YouTube support article Restrict YouTube content on your network or managed devices to achieve the same result. FortiOS supports applying Strict or Moderate restrictions using HTTP headers as described in this article.
In FortiOS 5.6 with inspection mode set to proxy-based, in a Web Filter profile under Search Engines you can select Restrict YouTube Access and select either Strict or Moderate.