I wrote a script to do that for you. [1] (and am having my server download the first fifty listed in the xml file). I'd like to point out that there's a little bit under a thousand talks, so I highly recommend you only download a few videos at a time. (each video is about 40 mebibytes. [2] Roughly 40 gigs of video.)

[1] http://pastebin.com/RXzTpbGt

[2] Average obtained by downloading 50 videos, and averaging those.

Edit: fixed bug in script.