This question already has an answer here:

I am gamer youtuber and I'm making gaming videos. I want to play with my best friend and make a video. I have a HDMI cable and a Xbox 360 HD AV cable. I've tried both of them but it still doesn't work! I've logged in a world, opened both controllers and I hit "START" but It still does not work. Can you guys help me please...

merged by badp Jan 21 '15 at 20:09

This question was merged with How can we play split screen in the XBOX 360 version of Minecraft? because it is an exact duplicate of that question.