I just always assumed that it was another example of the bad writing/horrible editing done on the contest rules.
It clearly states the top 3 will be there April 16th - 22nd. But online voting for top 3 is April 14 - 21st.
There is an implication that what they do at the park with be photographed/video'd and then we vote based on this extra material.
"The Grand Prize Application Process will require each Finalist Prize Winner to perform specific tasks, as designated by Disney Destinations, at the Walt Disney World® Resort and each Finalist Prize Winner will be videotaped and photographed performing such tasks (collectively, "Grand Prize Video Application")
... Individuals who go to
http://www.dreamcmo.com between 12:00 a.m. ET on April 14, 2008 and 11:59:59 PM ET on April 21, 2008, ("Grand Prize Voting Period") will be asked to view the three (3) Grand Prize Video Applications and vote for their favorite."
But I don't see how that's possible, do you? As I said bad editing or really bad math!