First, I found a website that talks about Buddhist symbolism, including elephants. The metaphor is perfect:
At the beginning of one's practice the uncontrolled mind is symbolised by a gray elephant who can run wild any moment and destroy everything on his way. After practising dharma and taming one's mind, the mind which is now brought under control is symbolised by a white elephant strong and powerful, who can be directed wherever one wishes and destroy all the obstacles on his way."
Second, the closing thought in the talk is from Kara S, about getting to know your personal elephant. Her comment reminded me of a conversation from Paulo Coelho's wonderful little book, The Alchemist:
"My [elephant] is a traitor," the boy said to the alchemist, when they had paused to rest the horses. "It doesn't want me to go on."
"That makes sense," the alchemist answered. "Naturally it's afraid that, in pursuing your dream, you might lose everything you've won."
"Because you will never again be able to keep it quiet. Even if you pretend not to have heard what it tells you, it will always be there inside you, repeating to you what you're thinking about life and about the world."
"You mean I should listen, even if it's treasonous?"
"Treason is a blow that comes unexpectedly. If you know your [elephant] well, it will never be able to do that to you. Because you'll know its dreams and wishes, and will know how to deal with them."
"You will never be able to escape from your [elephant]. So it's better to listen to what it has to say. That way, you'll never have to fear an unanticipated blow."
Coelho uses the word "heart," instead of "elephant," but I'm sure he won't mind the substitution.
Finally, I referenced a bunch of studies (in passing) in the talk, but didn't include any citations, because I ran out of time. If you happen to have links/refs to articles, books, videos, etc. in this area, can you paste them into the comments?
If you haven't seen the original slides yet, I'll leave these as teasers.