I certainly agree about the value of online conference videos. I've paid for them in the past and often turn to them on the web when I'm looking for info or solutions. And yea +1 for watching at double speed, 3x... that's pushing it. ;)
That said, it's easier for me to motivate myself to actually consume talks if I attend a conference. Which is to say, I seldom make time to watch talks on my own. My problem, for sure, but I think of conferences as retreats for catching up on tech. So that, in addition to the the human interactions and the experiential zeitgeist that comes with attendance make conferences still seem worthwhile for me.