Before I start, I have an obvious bias: I've been editing all the talks from the recent CUSEC 2009 conference to put online. It's time consuming, but I think it's worthwhile. So worthwhile actually that I wonder why today, with cheap-to-free bandwidth available, there are still conferences that do not publish their talks online.
My completely unfounded theory is that the organizers think that by putting their talks online people will avoid paying for a ticket, preferring to simply watch the videos when they get online. However, I think that that sends exactly the wrong message. While some conferences are clearly state-of-the-art and at the cutting edge of current knowledge, others are less so and would benefit from showing just how great the presentations are, confidently putting the presentations out in the world.
Another reason why conferences should be putting their talks online is that doing so would help them accomplish their stated mission: disseminating knowledge. Even conferences that are clearly run for profit and make massive gobs of money like TED (though TED does it for charity) put their talks online now. The cutting edge conferences have nothing to lose by putting the talks online since a year later there will be new and hopefully better solutions to the same or similar problems to discuss. The cutting edge information is simply put out there for everyone to have access to. Speakers at tech conferences routinely put up their slides but the slides alone are often just a fraction of the information conveyed in the talk.
It isn't even hard or expensive either. If you're worried about the costs of hosting the videos yourself, you can just pay vimeo 60$ and put up all your talks in "HD quality" and they'll foot the bandwidth bill.
If you run or are organized in running a conference, please do me, yourself, and everyone else a favor. Rent an HD camcorder if you don't have one available and tape the talks. Then throw them up online and blog about them and use them when you're promoting the next year's edition. Everyone wins.
