Here is what you can do :
Go into the NTA tab. If you don't have this already you need to add the Traffic View Builder view to your NetFlow Traffic Analysis Summary view. You can do this via the admin page.
Once you have Traffic View Builder you can build a view by dropping the list down and select 'Domain'. You can enter 'youtube.com' in the domain name. You select the vlan that leads out to your Internet. For me I'm netflowing from the VLAN to the firewall that leads all associates to the Internet.
That will give you total traffic over x time (depending on what you selected).
Hope that helps.
BB, this is exactly what i was after.
Thank you so much for your help.