Im in the process of using Handbrake to convert a large number of camcorder MTS video files to mp4 so that they can be played on both my PS3 and macbook. I've just noticed that Handbrake has converted some of the MTS files to .m4v even though I've selected mp4 in the settings. The .m4v files still play on both devices, but is there a reason for this? Should I continue to allow this to happen? Is my world going to end?