Install Missing Codecs with CodecInstaller

Ahh. If there were ever an appropriate name for an application, it would be this one. CodecInstaller allows you to peruse a list of available Codecs to install, should you need them. If you are not sure what codec a video you have requires, the same program can also analyze the video and tell you. If you have a robust video player, you probably already have the codecs you need, but if not, CodecInstaller will help you out.

Freeware app CodecInstaller searches your computer for commonly used codecs and displays which codecs you have installed and which codecs you need. CodecInstaller can even download and install missing codecs. Additionally, you can point CodecInstaller at a specific file and CodecInstaller will tell you exactly which codecs you need to play the file.

Source: LifeHacker