Not all videos load and problems with scratching from Numark controller

My music videos all load properly over from my iTunes playlists on my Mac Mini but not my brand new Macbook Pro 13" retina display…It shows all the files in my playlist but not all of them play. No sound and no video at all. I have a projector to send the videos out from my Mac Mini and also use it to project from my Macbook Pro.

Also, video scratching doesn’t work when I have my external MIDI controller (Numark Mixtrack Pro DJ) plugged in. It stutters to a point of being painful to watch and/or listen to the videos. I have to turn off the physical Scratch buttons for it to work properly but then it doesn’t allow for scratching at that point. Please help!