I installed the free version of RealPlayer, which has RealDownloader. That works very well on Youtube videos. I've used it for downloading videos for teaching (non gun related).

If you decide to do this, be careful. During the installation process, at the start, there are a number of boxes checked that you want to make sure that you uncheck. Free software like this comes with a lot of junk software that you probably don't want. Read each screen at the start of the installation carefully so you know what they want to install in addition to the program. You don't need the additional stuff for RealPlayer or RealDownloader to work.