a non-flying figure that starts in hindering terrain have his movement halved right?

what about a flying figure or a figure with leap/climb or phasing. Is their movement halved when they start their movement in hindering?

Yes. if someone who does not have flight, leap/climb, or phasing starts in hindering his movement is halved. The aforementioned characters ignore hindering for movement.

I figure with flight or L/C is not affected by the same rule, they still more their full distance. Thats why the Batman team ability with L/C is so nice since they can be in stealth and not be hinder by the terrain when they move out of it.