Okay, I'm going to post my far fetched theory since everyone else is. LOL!
I can't get over the weirdness of that lady seeming to high five the dreadlocks guy. I can't seem to shake the idea that that might have been a signal. It's weird to me that the two ladies approach, separate as they walk up to dreadlocks guy and dreadlocks guy stops, she high fives him, and then he suddenly starts moving with purpose. THAT's what makes me raise my eyebrow. You can see him at the edge of the screen looking like he's just sort of milling around waiting. And then the lady high fives him and all of a sudden he's off! And he's not ambling, IMO. He's walking with a purpose like he knows EXACTLY where he's going. Some people have suggested that she only high fived him because he approached her so she didn't know how to respond but there's no hesitation in her gait. She high fives him and keeps on moving.
I never really thought the white guy in the doorway was all THAT suspicious but the more I watch the more I think it's odd how SLOWLY he saunters out to follow Hannah. He's moving nowhere near the same clip she is and if he was concerned about her wellbeing, you'd think he'd move much quicker in order to keep up with her. Obviously if a block later the dreadlock guy has PASSED him so that he is now walking next to Hannah (as we see in the jeweler footage) he's walking slow.
So, my theory is that the woman who high fives the dreadlock guy was signalling him that a target was in the vicinity. Dreadlock guy high tails it over to where white guy is stationed. White guy follows Hannah so he doesn't lose her...trails her at a rate so as not to seem suspicious, hence the slow pace. Dreadlock guy passes white guy, catches up with Hannah and proceeds to charm her into the bar/car/apartment or whatever the sequence is that's next that we haven't quite determined.
Notice the woman who high fives him has a cell phone out. Maybe she was texting white guy who also has a cell phone out. Maybe she's telling him there's a target coming up and to step aside and wait for her to pass.
Far fetched? Maybe.
But you have to admit it is so weird how quickly and with such purpose dreadlock guy starts moving right after the high five when prior to that he was basically just standing there. Given that Hannah doesn't even enter the picture from top right until dreadlock guy is almost to the point where he's turning to cross the mall, there's no way he saw her in advance and that that's what triggered his move. SOMEONE let him know that she was coming.