said by ob1100 :My theory is uverse sniffs the traffic sees content as video see's it is not on the list of prime ip/segments drops it to low priority during prime time and walla endless buffering. When a VPN tunnel is created it can't be sniffed so it can't be prioritized so it is sent at full speed.
A VPN also takes a different route. I see similar with YouTube and IPv6 tunnels (unlike VPNs, traffic in those tunnels can be "sniffed").