I once had a dealer accuse me that I 'palmed a coin'--
right in front of his eyes--simply because he
lost count of the coins he handed me. He only 'figured this out' after I left his table at a show--and ran me down in near-hysteria.

In the OP's case, it seems like he had brought his own coins to the table, which would make me wary of stepping away too. Who walked away from the desk--who was being careless here? I just throw that out.
What I learned from my experience...is that I need to protect myself, such as counting the coins with the dealer. That said, protecting my own interests shouldn't replace
due diligence on the dealer's end. Frankly, I would be angry if a dealer told me the video looked 'suspicious'--then asked if I had 'accidentally taken it'? Come on, that's some really messed-up logic--and sore lack of
responsibility on their end. I'm glad it ended well

, but I would also be wary of being put in this situation ever again.