Ipod/Ipad Dock displays videos but cannot watch apps

I have an Ipad dock on both of my televisions and I have been able to watch movies or television shows under the "video" section of my Ipods/Ipads on my television but when I attempt to use some sort of an app to watch a movie or show and connect it to the dock to watch it on my television, I get audio, but no video. Does anybody have any idea why it won't let me watch these when using an app but will work fine when watching them under the videos tab?