I've used MainActorBroadcast a fair bit and I can honestly say I think it's the best the Amiga has available for producing animations with a sampled sound track.
The MainActor demo on Aminet is not the 'Broadcast' version, but the earlier v1.1 I believe. [Edit: It's 1.55] I've not heard of a 'Pro' version.
MAB supports AVI, FLI, FLC and BMP formats in addition to the native Amiga ones. I see no reason why you couldn't load in one format and save out as another (within the limited range provided).
I doubt you'll find much info on the Amiga versions at Main Concept. They no longer support the Amiga and it's long time since advertised the fact.
I've placed a few MAB animations on
my site if you're interested.
Cheers,
JaX
http://waveguide.v21hosting.co.uk