@stu (on 50hz rates)
"What exactly is a '50hz tv set' in 2009 ? It does not exist."
Everyone I might want to share videos has one. I expect it will be at least a decade or two before I can assume everyone has a flat-screen HDTV- capable set (so why even shoot HDTV ? In the hope the full resolution can be seen and shared in the future).
"I have numerous video cameras, some shoot 25fps, some 30fps, some 60 fields per second (i.e. AVCHD interflace). As long as your edit sticks to the same fps as the source footage, there is no problem."
But when you edit a combined film that contains material from them all, you have to pick one common frame rate for the result, and anything not in the common rate will turn jerky.
By the way, the NTSC rate is not really even 60hz (that would be too easy), but a funny fractional 59.94 or something like that. As I said, Blecch!