TED Talks: Who was General Tso?

During this holiday time of eating, I came across a very interesting presentation about Chinese food in America. I have long differentiated between authentic Chinese food and 'Chinatown' Chinese food, and I have pointed out that the beef-and-broccoli dish is part of the 'Chinatown' Chinese cuisine. The video below elaborates further.

Jennifer 8. Lee, a New York Times reporter with a number 8 for a middle name, "talks about her hunt for the origins of familiar Chinese-American dishes -- exploring the hidden spots where these two cultures have (so tastily) combined to form a new cuisine." (from TED.com)

Some of her facts may be wrong, but it's still an interesting thing to think about. Is this unique to Chinese food because of the broad reach of the Chinese? And what defines a dish to be even partially Chinese anyway?