YouTube Video Downloader provides GUI and command-line download interface
YouTube downloaders are a dime a dozen. Unfortunately, many of them are thinly veiled malware/adware containers, or they are just plain cruddy. What makes youtube-dl special is that it's cross-platform, free, open-source, and CLI-based. If you don't know what CLI means, you probably don't need it :). In a nutshell, though, it lets you download videos from the command line (you can see a CLI tutorial for it over at tinyapps.org).
Since youtube-dl is written in Python, it basically requires a Python interpreter to run. Luckily, a user who goes by the name of nishad created a standalone version for Windows and even added a neat GUI (pictured above) for users who are not comfortable with a CLI interface (or don't need it).
I tested it using a single video, and it worked very well. Once I set all of the options and hit the Download button, a shell window popped up and the script started executing. The GUI was very clear about this; it told me "please don't close the command windows opened" and had me press a button to signal that I really did understand.
The interesting part here, for geeks, is the CLI version. This could have some very interesting uses in scripts. If you use it to create something worth mentioning, don't be shy -- share it in the comments.