I listed some of my favorite Firefox extensions in a post earlier this year. One of them was VideoDownloader. If you watch online videos on YouTube and other sites that use Flash-based video, you can save those videos locally by using this extension. The extension has now been around for a while, so if you haven’t tried it, you should. Once you have it installed, you’ll find yourself using it more often than you think. For an example, I stumbled upon loads of old music videos from some of my favorite bands that people had uploaded to YouTube. I saved them after I watched them and now I can play them anytime and store them on my own machine.

When you save online videos locally, they are saved with a .flv file extension. This is a flash video file. To watch these files, you’ll have to download a viewer that plays this kind of file, such as the popular free FLV Player, which I use.