How to allow access to Gmail and block Youtube?

Question

Sorry for my bad English.

We are having difficulty with our Sophos XG.

We use the authenticated mode for internet access.

We need to allow access to Gmail, but we cannot allow access to YouTube for certain users

What is happening:
- Rule1: if the user does not have permission to access Gmail, nor Youtube, Youtube does not load;
- Rule2: if the user does not have permission to access Gmail, but has permission for Youtube, Youtube loads normally;
- Rule3: If the user is allowed to access Gmail, but does not have permission for YouTube, Youtube loads the page, including searches, but does not play any videos.

What do we need to do to solve the problem in Rule3? We need YouTube not to load the page in this scenario.
Thanks!

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Paulo Jose Bueno · Accepted Answer

Thanks for the contact and for the information lferrara and H_Patel . 
 However, we managed to solve our problem with "Rule3" through the support of the company BR2T (Sophos partner here in Brazil). 
 We had created a firewall rule that was in line with Sophos' proposal (KBs). So BR2T modified our firewall rule and used the FQDN block (*.youtube.com), instead of the "Application Police" / "Web Police" block. 
 It worked!