I think DD had a Bayley assessment when she was about 16 months actual (13 months corrected). We were involved in a research project where we did some activities at home with DD and recorded what she could/couldn't do, then we went to the Uni and they did the Bayley assessment with her. The idea was that, if the two are shown through the research project to tally, then rather than having to use a Bayley assessment, the parents could complete the home assessment and send it away to be looked at and developmental delays due to prematurity could be picked up without formal assessments (IYSWIM?!).
Anyway, the Bayley assessment was fine - just lots of little tasks to see if DD could complete them - putting objects in a bowl, sorting objects, building a tower of blocks, getting an object out of a closed container, copying actions, following simple instructions (Can you brush teddy's hair?), putting pegs in a hole, pointing to body parts, identifying pictures in a book (Can you point to the ball?), putting simple pieces in a puzzle (square, circle, triangle), making marks with a pencil, erm... Can't remember what else, but lots of little things like that - lots of praise, and no feeling of failure if they couldn't do something...
I don't remember any gross motor bits, but then DD was younger, and only just crawling, so maybe they missed those (or maybe I've forgotten them!)
Hope this reassures you!