One of the best attributes of an iPhone or iPod Touch is its ability to play back videos on an extremely high quality screen. I love watching video podcasts and other video from the iTunes Store when I'm on the go.
Sometimes, though, I have a video that I have downloaded from YouTube or gotten elsewhere online and I want to watch it on my iPhone too. Well never fear, here are the instructions for taking almost any video format, converting it, and putting it on your iPhone (or iPod Touch, it works for both).