I would like to block YouTube uploads but still allow users to sign in and watch videos.
If you are running SGOS 6.4.x and above, you can use the URL operation function to select YouTube and block the Upload Videos function as shown in the following screenshot :
If you are using a lower version, such as SGOS 6.2.x or SGOS 5.x, you can still block YouTube video uploads using policy. Follow the steps below:
YouTube uploads will be blocked using this policy. Alternatively, you can use CPL:
<Proxy>
url.domain="youtube.com/upload" Deny
Some reference screenshot below :