How do I convert a video file to an mp3 file for ipod video 5 gen?

I have a video file that I downloaded from youtube onto itunes and my ipod. But It is NOT a video however it is a radio commentary, but itunes and my ipod only recognize it as a video file and it wont let me add it to my music playlist as a music file. It keeps moving it to the video playlist section and it will only play it as a video. I see the file in my ipod, but I want it as a music file for my music playlist, not as a video b/c it is not a video. It sits on the same picture, there is no movement at all. I had no problem turning it into a music file for my ipod touch but the method I used for the touch wont work for my video 5th gen. Does anyone know how to do this?