Been lurking here from the beginning. Excellent reasoning and sleuthing going on. Wanted to return to HG's intent for a moment. To do that I'm using the McGrady's video from the Cavalier Daily. It is zoomed out to the original frame size and gives a more overall view of what's happening.
https://www.youtube.com/watch?v=Dy43pVr2Ixw
My belief is HG wasn't lost at all. Drunk yes, but not lost.
McGrady's is located on the front of a two block square and Grady's Ave. (which is right next to McGrady's Irish Pub) and is a dead end street. HG only showed up on the Shell video once going toward the downtown mall. Therefore she likely emerged onto Preston from either 8th, 7th or Albemarle St. and then turned to go toward McGrady's.
McGrady's Pub has no adjoined parking lot therefore patrons park in the neighborhood surrounding it. If HG came down 8th St. she would have already scanned the cars parked down that street.
HG comes into view on the McGrady's CCTV video and walks to the front corner of the outside patio at :56 in the video. She stops and scans the area around her. She then walks to the other corner at 1:10 of the video and pauses again. She then exits the video and is gone until 2:56 in the video.
My belief is she has continued walking up to 10th St. and around the corner to further scan for cars parked nearby. At 1:35 in the video we see I male standing just outside the outdoor patio seating area. He appears to be a bouncer to me. At 2:56 when HG rounds the corner back at McGrady's the male immediately strolls to the meet her at the top of the ramp HG is walking up. They meet at 3:08 in the video and she passing him very quickly and he returns to the place where he was standing.
HG, in my mind, has cased McGrady's for a car she is familiar with. Why go up the ramp? She can get a better view if someone she is looking for is on the outdoor patio and also ask the bouncer "Hey have you seen ____?"
At 3:36 in the video HG crosses Grady Ave. and pauses one last time to look up Grady Ave. at the parked cars. Not finding what she's looking for she continues on.
Her next destination is the downtown mall. Think of that feeling you've had sometime in your life that you're missing the party, the fun. Thus to close the distance she runs for a while and that's what's caught on the Shell video footage.