The advantage of streaming live events like sports games, is that by the time the copyright owner is aware of what you're doing and sends to a cease and desist letter, the even has been over for weeks.
There's also a huge advantage in serving ads over live video streams: You control the video content that the ads are playing next to. The reason that advertising on online video hasn't taken off is because corporations really don't want to play their commercials next to a video of a teenager lighting a fart on fire. You can avoid that problem by streaming live.
Any thoughts on streaming live events like Startup School? I'm sure that you'd have tons of viewers. It'd be a great service to people on hacker news. And, I'm sure it would be great exposure for you. Just a thought.