It'd be nice if they finally released the 90 minute version with the World of Pokemon prologue. I have it on tape and to my knowledge that version has never been released on DVD.
Wait... I'm pretty sure you're referring to "Ash's Journey", that short scene explaining how Ash got Pikachu and such narrated by Brock... it was included in the extras of Movie 1's DVD and is also an actual part of movies 4 and 5 (both of these start with it before going into the movie itself, with 5 being this way in the Japanese version too)
So they never aired it as the intro to the movie like 4/5 did but a dub does exist