I've just put together a little console app to crawl the myspc site and download all mp4 and pptx files from all sessions.
Note: It is not production code, it has not a real error handling and it does not handle authentication as you would do in real world apps ;-)
To use it, download it here and start it as follows in a folder where you want the files to be:
myspcdownload.exe "value_of_your_.ASPXAUTH_cookie_after_you_authenticated_with_a_real_browser" "value_of_your_WT_FPC_cookie"
Update: The second cookie seems not be relevant, so enter "x" for the second value.
You can get the cookie values by using e.g. IE –> F12 –> Cache –> View cookie information
If you want to make it more cool, you can also download the source here.