This next item was culled from a DVD release for Scooby-Doo to explain just how the cast came together. Well, most of them, anyway. This focuses on material from the ABC years (1976-86), hence Gary Owens (Blue Falcon) is here as well.
Heather North (Daphne) was, ah, moonlighting at the time, as she also appeared on Days of Our Lives during the 70's. She was actually the 2nd Daphne. Today, Nicole Jaffe (Velma), at least at the time this interview was recorded, had become an agent and made a 1-shot return in a DVD a few years back. Mindy Cohn, the current Velma, has come the closest to matching Nicole's original characterization. To think that, today, Casey Kasem (Shaggy) has been in ill health, but the real revelation is how he & Frank Welker had wanted to read for other parts. And, as we all know, Welker eventually would inherit the role of Scooby himself from Don Messick, but not before they'd tried out other actors after Messick had passed away. Some of Welker's facials during this video suggest the influence, in this writer's opinion, of comedy icon Red Skelton. Shoot, I'd bet he could recreate some of Red's classic routines.