After thinking about what Luc Lion and Radix wrote and reviewing the video from the side again, I've added an orange line to the illustration to show a pull up not quite to vertical and a question. I suspect that what was intended was something like a "sneak pass", low and out of the north, presumably taking advantage of the terrain. Or coming south down the river might have avoided high ground or a built-up area to the northeast of the airport.
The roll following the pull up then has a purpose, which is to reposition the plane of the loop so that the pullout is along the axis of the show line. However, not quite reaching the vertical does reduce the apex of the loop and the roll uses a little energy, both reducing the altitude gain expected from a straightforward loop entry.
The other problem is that the roll puts the show line behind the pilot and the amount of roll required to align with it might be difficult to determine at this venue. (In the usual loop at show center over a big runway, orientation is not a problem.) In the video, it appears to me that there is a lack of pull initially on the backside of the loop, which might have occurred because the pilot was focused on looking for the show line.
If he did not have a problem with orientation, the runway was smaller than normal as another post suggested and he might therefore have perceived that he was higher than he actually was (given that your entry speed and initial pull is supposed to result in altitude margin for the pullout, you "play" the pullout to safely use up the margin so as to level out at the same altitude as the entry).
