This is crazy.
Watch how carefully orchestrated it is by the group of perps running this scam. A street vendor probably selling stamps or postcards blocks his view, a second throws up a bigger visual block, while removing the lens. Initially the photo had the right guy, but a third member of their group grabs the photographer, pretends to see the thief running away, distracting him, while the original thief hands off the lens which is then thrown into a bag.
A have a motto when in foreign countries: Do not make yourself a target.