A few notes about Zemo:
1) he mentions that all of Hydra's secrets were released by Black Widow, though many were encrypted.
2) he says that he has experience with that kind of thing, and patience.
3) for the last year he's been studying and following the Avengers (and, presumably decrypting Hydra files)
4) if Bucky's handler had told him what he needed to know, he wouldn't have framed and released Bucky to get the info
5) it's Bucky who assumes that Zemo wanted the December 16, 1991 report because the multiple Winter Soldiers
6) when Zemo arrives in Siberia, he calls the hotel to ensure that he is followed
7) the first thing Zemo does in the hydra base is look through some dusty old archives
My assumption is that one of those Hydra secrets that Zemo decoded was proof of Howard Stark's assassination. He went to Siberia to obtain it and use it to divide the Avengers at the right time.
Because Zemo had to go through Bucky, he got the Avengers on his trail, but the UN bombing helped ensure the Accords would divide the team further, frame Bucky, get Cap to act against the authorities, etc.
But most importantly, he most likely knew through those released Hydra files that he'd find proof that could divide the Avengers even further. So perhaps it's not "Zemo got lucky that a camera was there and they had the footage," but because there was a camera there and they had the footage, Zemo knew how to find it.
Maybe