Playing video content on Windows still isn’t as easy as it should be, particularly if you’ve downloaded videos from bittorrent or usenet. Trying to find the correct codec to play video files can be difficult, because most users typically don’t know where to start, and they end up downloading the wrong files. This can also be dangerous as some codec sites distribute spyware and other nasty programs.
One tool that can help you find the right Codec is CodecInstaller as discovered by Techie Buzz. CodecInstaller will not only suggest missing codecs, but it will also tell you what codecs are actually being used to play a video file, which can find any codec conflict errors.
The most fullproof way to ensure that you can play any video is to follow the Guide To The Best Codecs. Since following this guide, I have never come across a video file that won’t play, and it also will help you play HD videos on machines with slow CPUs.