Sixty minutes sounds like it'd be a waste of time. There's so little that could happen in such a short time... most TV series pilot episodes are longer than that. Ninety at least would be tolerable.
Yeah, 60 min. isn't much. But maybe they're making more movies than one? Maybe two, or even three Advent Children movies?

Or maybe the 60 min. thing is just a rumuor. let's hope so.