Y-Mule is a great tool that allows you to download videos off from youtube and convert them into MP4, and MP3 files. This is great for making a personal library of music, but be aware that selling this music can get you in a lot of trouble as it violates copyright laws.
The interface of this product is easy to use and everything you need is all in one place, there are other pieces of software available that allow you to do the same thing, but not all of it is in the same place which makes it more of a hassle to use for the purpose of this.
Overall Y-mule is a fantastic tool to have access to but it needs to be used responsibly as it can cause a lot of issues for the user as well as the companies that post the music videos when it comes to such a touchy subject as copyrights.
The ability to download YouTube Videos
The ability to convert videos into other formats
Only supports the download of videos from YouTube