This is a public service announcement to my fellow medical students in their basic science years.  If your medical school is kind enough to use your tuition money to video record your lectures and post them on the internet for your later perusal, you do not -- I repeat -- do not need to buy any fancy software to speed up your lectures without chipmunking.  Your free alternative to the expensive software, such as 2xAV by Enounce, is VLC media player.  Just make sure that you have "Scale audio tempo in sync with playback rate" checked.  You access this check box through the "Show setting -- All" radio button and then the "Filters" tab under "Audio."

Quick and dirty screenshot of the dialog: