OK, I'll bite.
30 fps is fine as a frame rate for making successive frames of a film or video appear as smooth motion (film is usually closer to 24 fps), but the eye can respond to flicker at over double that rate. Ever used a CRT with a refresh rate of 60Hz? Ouch.
Essentially what I'm saying is that flicker is a separate phenomenon from jumpy video. Frame rates can be much lower than refresh rates and still appear OK.
Regards,
Torben
P.S. - Yeah, I just pointed that out to be a PITA.