Because the act of shaking the controller to get your character out of the shack and playable is such a silly thing. Plus there is no UI loaded in at that time either. I would equate it to the elevators in ME 1. I could be wrong, but that is my guess.
*** Edit****
Reading further into the thread, it looks like it is pointed out that this only happens in the first level. In that case, unless there is some other obvious masking tricks being used, it seems like the wii version just has an easier time loading in the content. Probably because of a faster read speed on the drive and less memory intensive assets being used.
But Donkey Kong was standing in place ready to be moved while the DkCRTF level was still loading up. Then the clips skipped to gameplay so it may have been even longer than was shown.