Thanks for posting this presentation.

Bad news:  Sound for this slideshow won't play in Silverlight 3.0.50106.0 (from silverlight.net) in IE 8.0.6001.1870 and FF 3.6, Win XP SP3 + all updates, AMD Sempron 1.8GHz.  I don't think it's a CPU issue, because other videos do play with sound, such as this one uploaded by Jossie on the same day (Sept. 23, 2009):  http://channel9.msdn.com/posts/Jossie/Connected-Information-Security-Framework-Core-Components/ and  http://channel9.msdn.com/posts/Jossie/Technical-Preview-for-CATNET-20/

Good news, workaround: copying the URL from the embed HTML ( < /> icon) and pasting it into Windows Media Player 11 "Open URL",  the video+audio streams perfectly:

   http://ecn.channel9.msdn.com/o9/ch9/6/9/6/3/9/4/antiXSS31_ch9.wmv

The trouble?: WMP11 says the audio codec is: "Windows Media Audio 10 Professional, 128 kbps, 44 kHz, 2 channel 24 bit 2-pass VBR".  24 bits seems like overkill for a voiceover, and Silverlight 3.0 won't play it. (Or is it a container problem?) 

Suggestion:  In future, encode audio for WMA 9 and/or 16 bit for maximum backward compatibility.