Promostudio sounds way better. Domains should try to stand up to the phone test, and viddio most certainly does not even come close.

I've bought/sold a number of domains and have a pretty good idea for pricing. I wouldn't pay $100 for viddio.com

Promostudio is excellent (assuming it's not trademarked already). Very professional and easy to spell. Worry about your product, your domain is plenty good.