Hey Peter,
I am sure that it would be more cost effective to reshoot the event, sorry. Not what you want to hear, I understand. However, even if you could get the dancers on their own, could maybe save the day.
In any case, several questions comes to mind:
1) Is this a multi-cam shoot? (Do you have other shots where the feet appears?)
2) Depending on answer to question 1. Do you actually know what the missing feet looks like?
3) If yes to 1 & 2 above, maybe try and create at least 1-frame of “clean” plate and work your way from there. You may find that at 720p resolution, if that is what it was shot at, that the “camera” will be less forgiving than at 4K.
But unless you have extremely deep pockets, it is highly unlikely that it is an easy job. Though if the clip is “only” 7 seconds long, everything is possible.
One part to try is to cut out the speakers and everything below the stage edge. Pop some Chromakey Green or similar to fill, and then ask Adobe regenrate it. You could also ask any of the mainstream A.I. tools coming in to play. But it is highly likely that you get comedy rather than professional dancers.
Atb
Mads