Much like music files, video files (MPG, AVI, and so on) work out of the box in Mint and will typically play as soon as you double-click them. Interestingly, Mint features two video player programs. The default player is simply called Videos, but VLC is installed as well. It's not certain why Mint features two video players, but if your file won't open in Videos, it's likely that VLC will be able to play it. VLC is a powerful cross-platform video player (it's available in Windows and Mac OS X as well) and is able to play just about anything. If VLC is unable to play a video file, it's likely that nothing will.

If you end up preferring to use VLC, it's easy to switch the default. In order to do so, right-click on a video file, click on Properties, and on the very first tab, you'll see a drop-down menu that will allow you to select the default player. Please keep in mind that you'd have to repeat this for all video file types. For example, setting the default player for...