Have you checked all the mute buttons to make sure that they are unmuted and that the sound volume is turned up?
- There is a mute button and sound control on your computer
(PCs: lower right; Macs: upper right).
- If you use computer speakers, they may have a separate mute button and/or volume control.
There is a mute button on the video player (lower right corner of the video - you may need to hover over the video to see it).
There should be 5 vertical bars at the lower right corner of the player. Do you see them? Are they all showing in color?
Playing videos clips also requires Flash Player. Please check to make sure that Flash Player is enabled on your computer and browser. You can download a free copy of Flash Player here: http://summituniversity.org/flashplayer