Man of Honour
Seems like a bit of a security vulnerability if an external user can distinguish the streams for different applications separately - I always assumed that at the most basic level the data sent over a protocol would be combined upto the max packet size and indistinguishable.
It's the nature of how IP works - you can't bundle the traffic for iplayer and youtube together because they're going to different places.
Is it a security flaw - well, properly analysed it can give up users and usage patterns, it's a fundamental part of how IP works though and it was designed in an era when those concerns weren't really valid as the people designing it kind of only expected universities and governments to use it...