Here are two versions of the video attack on Romney by Gingrich's Super Pac. It makes the case that in the much-admired "creative destruction" of capitalism, Bain Capital under Romney's leadership devoted itself to destruction and left creation to others.
The 3-minute trailer:
The full 28-minutes:
The full version is also available here.
For a brief explanation of the private equity business model, I recommend this Mike Konczal interview of Josh Kosman, author of The Buyout of America: How Private Equity Is Destroying Jobs and Killing the American Economy,