There's more to video on Xoom than shooting your own personal video and sharing it via the web or watching it in the Gallery. You can rent or purchase movies and professionally made videos from online marketplaces, although, for now, this media currently comes only in streaming format. (It's not actually downloaded and stored on your Xoom so you have to be online to watch it.) You can get streaming video from various places; Amazon is the most popular at the moment (although Amazon's instant video feature is a U.S.-only service right now). Of course, you can watch movies and videos people put on the Internet, including what you find on YouTube, CNN, and the like. You'll probably need the Flash Player for that, too.
Additionally, if you have movies or videos on your computer, you can copy those and watch them on your Xoom using the Gallery, provided they are in a compatible file format. (Don't worry, if they aren't, you'll be told they won't play when you try to copy them.)
And as you'd suspect, movies you purchase to play on your iPhone, iPad, Zune, or other device won't play without using third-party apps or converting them to a compatible file format prior to copying them to your Xoom.
HOW CAN I DISCOVER THE FILE TYPE? If you have movies and video on your Windows-based computer and you want to find out what type of files they are, right-click the file and choose Properties. You see the file type under the General tab. Similar options exist for other computer ...