In an explicit deployment, users are unable to view ustream.tv videos. The web site loads but displays an error when users try to play any videos. 

This issue is caused by the Ustream.tv video player. It does not use the browser's proxy settings and does not recognize any proxy auto-configuration (PAC) file. Packets are sent to the Ustream.tv servers directly/transparently instead of forwarding them to the proxy. 

Users cannot play videos because of the following:

• If packets are forwarded to the ProxySG, the ProxySG never receives the requests; the packets' source IP is that of the user and the destination is the internet IP.
• If your network does not allow transparent traffic, packets are in most cases blocked by the firewall to which they are routed.

To resolve the issue. perform the appropriate fix:

• Route traffic destined for the ustream.tv servers to the ProxySG appliance and make sure the traffic is intercepted.
• Adjust the rules on your firewalls to allow transparent traffic through for the Ustream.tv servers.

Refer to information provided by Ustream.tv for what IP addresses and ports they use:

ustream.zendesk.com/entries/21119702-Opening-Firewall-or-Proxy-Ports-for-Ustream-Broadcasting-and-Viewing