Well, the Video tin gives you 30 Mbps, so I would try up-priorising stadia, and only stadia traffic to Video, that might already solve the issue and seems considerably less involved, and with a bit of luck that already is enough 'bandwidth' to make stadia happy.
That said I like the idea of moving everything else to bulk as that gives sort of a two tier precedence hierarchy. Clever, but in this case maybe not required.