Get a TV tuner card for the laptop. http://www.newegg.com/Product/Product.aspx?Item=N82E16815116034
A DVD player should have a standard video input you can use as a pass-through also.
Note these things can only read decrypted content, so any scrambled channels will not work.
Just read that you want the TVs to see what's on the laptop as a channel. Basically you can set this up, but you need some hardware here, check with some hotels, they have their own custom channels and can probably let you know who set it up for them.