I'm pretty sure the eye cannot actually physically determine the difference between 30 and 60. There is a lot of debate about what the eye stops seeing at fps, and as I noted above some scenes/types of video can be improved at 60 fps.
Those videos could be enhanced (haven't had a chance to look at this, just got back from a 6 day paddling trip).
There are just physical limitations to what the eye can see (and by eye, I mean eye/brain combo).
Anyway, google frame rate and vision, or something, and there should be tons of papers written on visual limitations.