MPEG-2 Video File Format
According to the Wikipedia page on the subject, the "MPEG-2 is widely used as the format of digital television signals that are broadcast by terrestrial (over-the-air), cable, and direct broadcast satellite TV systems. It also specifies the format of movies and other programs that are distributed on DVD and similar disks. As such, TV stations, TV receivers, DVD players, and other equipment are often designed to this standard."
MPEG-2 files use progressive encoding, which requires viewers to download a video file in its entirety before being able to view any of its content.
MPEG-2 files also use temporal compression, which reduces the amount of data stored within a sequence of frames by employing key frame technology. Rather than storing every pixel in each frame, temporal compression stores a key frame, the only the information which is changing between key frames. Quality of the footage can be significantly lower than progressive encoding formats as a result of temporal compression being used. Temporal compression also has the drawback of not allowing future editing of the file.
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