An apparently little known feature of Windows Media Player (judging from the number of people who are surprised when I tell them about it) is the Fast Forward button, which allows you to watch (and listen to) clips at 1x, 1.4x, 2x and 5x the original speed. I generally watch the PowerPoint section at 2x and scoot back to 1.4x for code demos.
The cool thing is that WMP seems to use a compression technique which cuts out silence in the audio rather than just playing everything at double speed (so it doesn’t affect the pitch). Note that you can also play at slower than real time if you want to. There’s an entry available in the WMP help file that gives you all the details.