For When You Press "Play" and Nothing Happens

Mark Osborne:

Simple, fast and powerful media player:

• Plays everything: Files, Discs, Webcams, Devices and Streams. 
• Plays most codecs with no codec packs needed:
• MPEG-2, DivX, H.264, MKV, WebM, WMV, MP3... 
• Runs on all platforms: Windows, Linux, Mac OS X, Unix... 
• Completely Free, 0 spyware, 0 ads and no user tracking. 
• Can do media conversion and streaming."

Get VLC here.