I'm often at events mostly to meet people, aka hallway track etc. I do go to sessions too, in part because video posting can be unreliable/very delayed but also because I know I'll often never get around to watching the videos anyway. That said, keynotes at large events I tend to watch streaming as I have very little interest in getting crowded into a room with 10,000 of my closest friends so I can watch the speaker on the distant stage up on a monitor :-)