I run a TMG 2010 at home as my reverse proxy for Lync and Exchange lab. But internal I had some complains from Apple Iphone / Ipad users including myself I couldn’t stream Youtube 
Found out that Apple Youtube app doesn’t like the forward proxy in TMG…
But how to resolve it? I know, you want to have a proxy for monitoring, scanning etc. But for me at home and maybe in some office scenario’s this might help to allow iPad and iPhone users to stream their video’s.
In the TMG console in the Web Access group I created a new rule:
Give the new rule a appropriate name and hit next:
Its still useful to allow the traffic:
Choose to add protocol and choose new protocol, No we are not using the HTTP, we going to create a new protocol outbound for port 80, so here we go:
In my name convention I always use for predefined protocols the convention:
protocol / number [/ = outbound and = inbound] so in my case TCP/80
Choose new and specify here outbound tcp 80 to 80:
Choose no for secondary connections:
And Finish the new protocol wizard;
Add the created protocol:
Define your sources who can use this rule. This can be a complete network or a group of computers or a specific subnet. In my case I use internal network and VPN clients;
In the destination I choose to create a new URL set as I only want *youtube.com/* to use this rule. Click new and choose URL set:
And entered the url and it OK:
Add the new created URL set and hit next:
As we need to be anonymous choose all users:
And we are almost done. Hit finished:
If you were smart to copy the Allow Web access rule you need to disable (clear) Force fulle content request in the malware inspection tab:
Then apply the changes :
Let’s monitor the network:
I specified the iPad ip to monitor real time. You see the normal web proxy still works for all other traffic:
And when I open the Youtube app from the ipad:
You might also see in your monitor that the rule give a connection aborted, but the stream continues on my ipad. When I look in the error it still refers to the Web Proxy filter and for me looks like it categorize the link but does further nothing.
So I need to figure out what that exactly is. For now my wife and her son are happy they can use iphone and ipad to stream youtube videos.