If you only want to do this for a few photos, you just need to (eg) record the Times Square webcams for a couple weeks, then find a couple of recently tagged Times Square photos, make a good guess as to time-of-day and exact photo spot and scrub through your recorded footage from those times until you see someone in those clothes with that pose. It'll take a little while, but with this project you only need to do it a few times.

Keep in mind that the person doing this has all the context from the Instagram account's other photos and captions. Perhaps the same Instagram account made it really obvious what day this trip was happening, which would narrow it down enormously. We don't have that context, but the artist putting this project together has a free choice of which photos to investigate, and in Times Square or in front of Wrigley Field you can surely find some Instagram posts where it's obvious from the surrounding context what day and time it was taken, EXIF data aside.

And that's assuming the artist didn't just hire these people to show up at Times Square at a convenient time for him to press "record" on the webcam.

Not sure if Instagram makes the exif data available

Edited to add comma.

”No, exif data…”

(taken from yesterday's posting of OPsec tools: https://news.ycombinator.com/item?id=32951406)