surely also depends on implementation
I work for a large corp, and to avoid heavy network traffic over both it's ISP and it's own network, it sent everyone a link to it's own hosted stream. That way the majority of people watching were feeding through the on, controlled route rather than lots of random connections over the web.
Another company I know of setup screens in it's own cafe, so most of the staff went to watch it there rather than on a little window over the web - as they put it, better to lose staff within their own building for 90 mins than the network grind to a halt or they all bugger off the pub for the rest of the afternoon
I think networks/companies are just getting smarter about how they handle this stuff...