In any explorer that uses the Web view - including those in the Search Results window - you can play a sound or video file without running a separate program. To play back .avi, .mpg or .wav files, make sure that Enable Web content in folders is checked in Tools-Folder Options-General, and make certain that Windows Media Player or RealPlayer is installed.
Then select the multimedia file. In the Web view's file information pane, a preview window will appear with the first frame of a video file, and a slider bar with player controls will appear for sound files. To listen, click the Play button. To check out frames of a video file, slide the bar beneath the preview.