VirtualDub (32-bit version)
This is a wonderful file for video processing geeks. VirtualDub is a free, open source application that is something of a "photoshop" for video. To start off with the basics, it'll capture video and let you save it. Even if that's all you want to do, this program is worth the download. But it does much more as well.
Its full features are beyond the scope of this review, but it's a very good tool for cleaning up and trimming video, in particular if you want to use it in concert with a more fully featured video editing program. You'll be able to crop video, compress it, remove and replace audio tracks without changing the video, and much more, including using filters that allow you to sharpen and blur. You can even delete individual frames. Highly recommended.
Note: This software comes in 32-bit and 64-bit versions. This is the 32-bit version. If your 64-bit PC is running 64-bit XP or 64-bit Vista, please download the 64-bit version instead.