Pdc-downloader is a project mainly written in C#, it's free.
A console application that downloads all powerpoint and video content published from the PDC
A console application that downloads the power point and video presentations from PDC 2010.
Example Commandline
pdcdownloader wmvhigh
This will download the powerpoint files and the high quality wmv files.
Other video options: wmvhigh wmvlow (default) mp4high mp4low