It's about ninety minutes long, but Krauss is a fine speaker, so the time seemed to fly by for me. Jump to 03:55 if the intro starts seeming tedious.
Also of interest: First, the Krauss talk appears to have been organized by The Science Network, which I've mentioned a time or two before. You might like to visit their page for this talk and see if anything else grabs your eye.
Second, D.G. Wills Books has a YouTube channel, featuring other people who have
pimped spoken there. For example, Christopher Hitchens in 2006 (i.e., pre-God is not Great), discussing the book he wrote on Thomas Jefferson, and answering audience questions on other topics, as well. [Added: which just keeps getting better and better, the farther in I get.]
P.S. Lawrence Krauss's home page, just for completeness.