"The previous poster has it right...the PAL broadcast standard runs at 25 frames per second, while NTSC runs at 29.97. Since it has 4 less frames per second, the run time on a PAL video/DVD will have less of a run time than it's North American counterpart..."
That isn't the way it works. Well, your conclusion is right but your reasoning is wrong. PAL having less frames per second than NTSC would make PAL have more of a run time, not less. For example, suppose a movie has 150,000 frames. At ~30 FPS the run time would be 5,000 seconds (~83 minutes), and at 25 FPS the run time would be 6,000 seconds (100 minutes).
What's really happening is this: this movie was shot on film at the standard 24 FPS, which is 1 less frame per second than PAL. My copy of this movie has 146,832 frames, which gives the following run times:
24 FPS = ~102 minutes
25 FPS = ~98 minutes
When a movie shot at the standard 24 FPS is transferred to PAL video it is simply sped up to 25 FPS. However, when transferring it to NTSC video, it's more complicated. You can't just speed it up to ~30 FPS, because that much of a speedup in the motion and audio would be very noticeable. So they use a process known as 3:2 pull down:
https://en.wikipedia.org/wiki/Three-two_pull_down
Since this process adds extra fields, the run time doesn't change compared to the original 24 FPS film. Actually, it changes ever so slightly because the frame rate minus the added fields is 24/1.001 (which = ~23.976 FPS). That's to keep it compatible with the version of NTSC that allows for color broadcasts, which was reduced from the original black & white 60 fields per second / 30 frames per second to 60/1.001 (~59.94) fields per second / 30/1.001 (~29.97) frames per second, which was done way back when in order to make room in the allotted bandwidth for the color signal.
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