If you have problems when trying to play videos or audios from Media section it may be because of your browser media association for those kind of files.
A solution is to use the QuickTime plugin to play audio and video in your browser.
The QuickTime application from Apple, Inc. includes a browser plugin that enables you to play movies and other online media in your browser. QuickTime is included on Mac systems and is available for Windows.
Download link: http://www.apple.com/quicktime/download/