He's taking about the floor framing. Richard, my guess is that with Houston being close to the Gulf that there are some increased wind load requirements and they didn't want shear walls. Not sure what the seizmic requirements are there either. I will say that I typically only see flat slab used here in condos, low rise hotels, parking garages, etc. where floor to floor hts. are king. I don't have a lot of experience in commercial work though, so someone else might be able to provide a better answer for you. Personally, it seems I see more composite steel frame and slab these days than anything else.
I will also say that my structures professor had a bias for beams and that might be pervasive.
They might also be doing a bit of fast tracking and wanted some flexibility.
edit - actually Richard, if you check the aerial, they've got a massive span and cantilever thing going on in the main part of the garages, aaaand in the interior shot it looks like they've got some column offsets they're dealing with.