When you view a TV/comp screen through a camcorder/camera, why are there grey/white stripes?

Question

When you view a TV/comp screen through a camcorder/camera, why are there grey/white stripes?

Answer 1

while a computer or tv screen appears to have a constant image, it is infact being refreshed 20 to 100 times per second.  it appears constant because your eye has a persistance of vision and doesn't notice the changes. However a camcorder has a scanning sequence to obtain the image from the CCD, and the combination of display refresh and scan rates results in patterns similar to moire.