So, last night I confirmed the Media App you can find in the Xbox Store on your Xbox One can be used to play .mp4 movies. Which is huge to me! Simply find a hard drive, or flash drive, and format it to Fat32, put the movie onto the flash drive, plug it into your Xbox One, and go to your Media Player application, launch it, click your USB or HD and boom, you can watch whatever media you choose or even play music off a flash drive. I have been waiting for something like this for a long time... -Iamcoolz