Since 24 doesn't divide evenly into 30 that means that when converting film to be shown on TV they have to stretch some of the frames out to fill everything up, in a process called either 3:2 pulldown or 2:3 pulldown. (3:2 pulldown wins the google fight, but for some reason wikipedia went with 2:3 pulldown.)
Basically they subdivide both sets of frames my 6, so you end up with sets of 4 frames on the film side, and sets of 5 frames on the NTSC side. Each frame is on the NTSC side ends up being a combination of two of the frames from the film side. (The wikipedia link has a pretty good illustration of this.)
It gets a little better with conversion to 60fps, where they alternate between repeating each individual film frame either 2 times or 3 times.
And of course with 120hz refresh the problem goes away entirely since you can divide 24 into that easily.
A lot of videophiles claim that the difference is obvious, but of course they would claim that. I don't suppose anyone has personal experience with the difference between 60hz and 120hz tvs using a blu-ray player?
I suppose that really shelleycat and i just need to go to Best Buy or some other place that has properly set up display TVs and see if we can tell any difference between 60hz and 120hz, and any difference between regular fluorescent lighting and locally dimable LED lighting.
(Have i mentioned before that shelleycat is convinced that i get more fun out of the research involved in planning to buy something than from actually buying it? =)