I believe his point was that the effect of looking at videos from Greece while imagining the consequences for the economies in the rest of Europe and those consequences spreading to the US while suddenly watching the Dow fall 1000 points was harrowing, to say the least. Not that one was caused by the other, but that it a lot to take in in one go.

I'm sure watching the Dow fall like that while watching videos from Greece was scary, especially to people that are already too aware of the fragile state of the world economy.