This is the best way by far to watch TV shows and movies stored on your computer.
Videostream for Chromecast previously only worked with .mp4 and .mp3 files but it now supports all file formats.
It is simple to use and it works incredibly well.
Once you've downloaded the extension for Chrome click 'Select a movie to play', select what you want to watch, click Open and the video will appear on your TV in superb quality.