A - First, check to make sure if the video description says "No Audio". Some movies have no audio track. If the movie is supposed to have sound, but you can't hear it, download QuickTime (Apple.com/Quicktime) or VLC (VideoLan.org). For Windows, you can also Google "k-lite codec pack", then download and install it. For Mac OSX users, install Perian component (perian.org) .