Nope, actors were hired to read off of typed transcripts from the original story meetings. I don't think any audio was ever recorded. I have no idea who portrayed Walt, but it wouldn't surprise me if it were Jim Cummings or Corey Burton, both of whom are very talented voice artists that Disney uses frequently.
I'll ask my fiance when he gets home. I remember he said he recognized the voice from some documentaries or something. (He works in radio and is really into voice work).
Whoever he is, I think he did an excellent job with the nuances that Walt had in his voice.
Slightly off-topic. but speaking of classic Disney voice artists, who was the announcer who did the intros to the Disneyland/Walt Disney Presents/Wonderful World of Color TV series? I assume it was the same man thruout?
