Format Factory is a Windows-only piece of software that will convert any video format to any other video format. It will do the same for audio files. It will do the same for digital photos. It is free.
I have been using it for six years in my job as an eLearning producer, and my hobby as a “Let’s get this movie to play on the computer, the iPod, the iPad” and so on.
I have paid for and used virtually every other video format converter, and this one is the clear winner for ease of use, flexibility, speed, and being able to stack up several conversions and have them run serially. You can even add a new task while it is busy working on another.
Want to rip a DVD to play on your iPad? Easy.
Want to convert a video file to Flash? Easy.
Want to extract audio from a video file? Easy.
Want to convert your home videos to YouTube format? Easy.
It has built-in settings for iPod, iPad, Blackberry, Asus, PSP, and many other devices.
Advanced tools for the tinkerer allow you to choose the codec, aspect ratio, bit rates, and other settings. You can also trim segments from the video, or join video files. You can name and save your settings.
Did I mention it was free?