The first and most common option is to simply copy and paste the video link you want to watch into the program window. In just a few seconds, your video will have been downloaded into your chosen folder in FLV format.
The second option, less common but equally as easy, is to use the browser that comes built in to the program. The only problem here is that the thumbnails often look different to the real thing, and this makes it a little awkward to find the video you want.
Yahoo Video Downloader is an interesting tool that, despite having a lot of adverts in the main programme window, does everything it promises to do quite efficiently.