Grand Marshall Pre-Parade for the Parade of Dreams.
For a couple of months before the 50th anniversary started in May in early 2005 it was used as part of Mickey's Magic Kingdom Celebration Cavalcade, a sort of miniparade in the lull up until parade of dreams debuted. The Grand Marshall stuff started later towards the end of the year(well before year of a million dreams began... which it's now used for. The grand marshall family used to be randomly selected just for fun, now the grand marshall is whatever family wins the night's stay in the mickey mouse penthouse suite at the disneyland hotel);