Sad Guys on Trading Floors

Just for fun - this is so hilarious, especially the funny comments!
Sad Guys on Trading Floors.
And now I have to show my ignorance of Wall Street, so please help me out. I understand why the average person on the street gets upset when the stock market crashes, but why do the traders get such shocked looks? Do they get paid based on how the trading goes? And who the heck ARE the people that are on the trading floor anyway? Individual traders, or people who work for companies, or what?? I told ya my ignorance is showing. I really want to know - so if you know please comment!