DVD out on a laptop

My friend has a DVD problem. The issue is that she can watch DVD movies on her laptop, but when she tries to play them on her tv all she gets is a black screen. She has one video out connection on her laptop and she has it connected to the yellow video in connector on her tv, but the picture is black. She does get audio, but it comes from her laptop because their are no audio out connections on the laptop. She has used several different types of dvd playing software, but she gets the same result all the time. Anyone have any suggestions on how to remedy this?

video overlay only works on the primary display, switch the TV to be primary and it will work

Uninstall the DVD player on her laptop and reinstall it. It should be be able to play off the laptop (and the screen) directly... If not it's either a DVD problem, DVD software problem. Or her DVD drive is dying on her. (I'll believe one of the 1st two before the 3rd).