She appears to be highly intoxicated so, IMO, the unreasonable and unlikely become possible. That includes walking into a fenced-in lot and climbing the fence.
Having watched the Disappeared episode, and after seeing the security videos,
IMO it does appear Kirsten is intoxicated based on the way she's walking. She appears a bit unsteady, especially in the final video, just before the camera glitch begins.
MOO.
IIRC, her phone was turned off, or stopped working for some reason, around 12:30AM, as phone calls from her mother went unanswered. This is about the same time Kirsten began walking away from the Irish Mutt parking lot.
One thing that is not mentioned in the Disappeared episode is the length of time it took Kirsten to arrive at the YMCA parking lot (1:59AM), which is roughly 90 minutes after she was seen in the Irish Mutt parking lot. The reports I've seen indicate the walking time between the bar and the YMCA is about 15 or 20 minutes. Given the fact that Kirsten had been drinking and appears to be walking somewhat erratically, it likely took her longer to walk this distance.
Detective Bockting indicates Kirsten was seen on video walking along Shortridge Rd. around 12:40AM, however, that leaves about an hour of time that is not accounted for between the sighting on Shortridge Rd and her arriving at the YMCA.
Another point to consider is that the detective indicated that this is a 'high violent crime area'. How, or if, that may factor into her disappearance is unclear, but it does seem to be a fairly risky area to be walking alone at 2:00AM, especially after spending the evening drinking.
At one point in the episode a large hole is shown in the YMCA fence, large enough for a person to fit through. It's not indicated exactly where this hole is but
IMO this could be facing the Abbey Meadows Apartment building. If this hole in the fence existed at the time Kirsten was last seen, then it's conceivable she could have exited the YMCA parking lot, heading towards the apartment complex.
At this time there's no evidence to indicate how and when Kirsten exited the fenced in YMCA parking lot. We do know that when the camera began working again at 2:30AM there was no sign of Kirsten.