In my experience this IS video noise from a ground loop. Tvad's solution may help if you are not getting a good ground because your connections are loose. Try an isolation transformer on the co-ax from your cable. If that works you know the problem; not sure about the solution if you have digital cable.
how to remove video noise on my plasma? DESPERATE
this is only a problem on cable. DVD is fine as are any digital channels. i have constant "noise bars" traveling from top to bottom on the tv. is this 60hz video hum? what can eliminate this? anything i can put inline from the cable? DESPERATE FOR ANSWER.