I was playing a cd in dvd player I recently purchased for some relatives when I noticed something odd. On the last song, I looked at the tv screen and noticed several horizontal lines that were on the top 3/4 of the screen. They were sort of flashing/flickering in rhythm to the music.

What would cause this flickering? While it's fascinating to watch, I don't think it's normal and would like to know the cause. The dvd player is a dvp 5140/37. They have an analog tv, vcr, analog cable, and a rf modulator connected to the dvd player. I hooked it up myself and everything is connected properly.