That is the MP4?
MP4 is a format container multimedia used mainly to store tracks of audio and video, especially the codificadas as the standard MPEG-4, but can store other contents like subheads or images. It has a structure that does it felicitous for "streaming" of contents multimedia.
The extension MP4 to has been popularized by Apple the one who initiated the use of the extension ".m4To" in his software "iTunes " and in his popular players of audio "iPod " to distinguish between files MPEG-4 of audio and video.
Also incorrectly called Mp4 to portable players that have a screen capable of playing videos and images.
This is actually a marketing strategy that tries to give the impression to consumers that an Mp4 player is more than an MP3 player for the simple and logical numerical superiority of the first name.
However, these players are called because they tend to play MP4 videos in MPEG-4, as AMV.