Web Filter Youtube Exception

Hello friends, 

I have a question i hope that can help me.

I have a web filter policy to Video Hosting category. It works fine, but now i want to allow youtube access, i made the exception following this steps: 

1. Login to Firewall Web Admin > Click Web > Click Exceptions
2. Click “Add exception”
3. Add an exception name in the “Name” field
4. Enable “URL pattern matches”
5. Click “Search / Add” and input ^([A-Za-z0-9.-]*\.)?youtube\.com/?
6. Click Save

It "works" i can enter to youtube site, but any video can be loaded. I try to add a custom category, and the result is the same. 

It is something tha can i do to solve this issue? 

My best regards