There is a huge difference between watching the talks and actually being there.

50% of the value is the content of the talks, which supposedly described the latest and greatest.

Just like in academia, the talks are actually dated: they have been prepared months before and don't really represent the latest. To know the latest, you need to chat with various people to find out what they are working on right now, that they can't quite announce yet.

What's on stage is canned, in a sense. If you want to be in, you got to be there in person to catch where the future is.

This has held true for me both in academia (research) and web 2.0.