In addition to my comments above, a figure can be seen standing just in front of the cameramen from 30-40 seconds and 51-52 seconds in this video. The figure appears to be the right height, shoes, cap, and body shape to be Frank. The figure is definitely wearing a bib. It can be seen at the 32-second mark. A high-res of this photo might show the bib number. In the 30-40 second sequence, the figure does a calf stretch on the curb, similar to what we've seen in other photos.
Later at the 1:04 mark, Frank jumps in wearing a reversed t-shirt over a long sleeve T. No bib is visible. Remember, this is time lapse photography so there is plenty of time from :52 to 1:04 to reverse a t-shirt.
Derek, do you have the high res photo? Can you read the bib number?