YouTube Download Plus was just one of several dozen Firefox extensions claiming to be the best video downloading tool available in the 21st century. Frankly, I thought I'd try it because I was looking for something simple and that worked as advertised, two small criteria that, sad as it sounds, most of the other extensions I had tried failed to satisfy. But this extension satisfies BOTH of them: it's simple to use, doesn't take up much space and does exactly what it claims to do: "Download YouTube videos as MP3 or MP4." This may sound like a simple request, but it's not. Or at least it WAS not. Thanks to uepselon, it actually HAS become so, and you have my gratitude. :)