I love this, a very short snippet video from venture capitalist Ann Winblad of Hummer Winblad Ventures. This is one of Stanford’s eCorner videos. I like their summary:

Ann Winblad advises entrepreneurs to boil down their business plan and tell everyone in the company the top five assumptions for success.  “As time goes on, turn the assumptions into facts,” says Winblad. She also reminds entrepreneurs to constantly reevaluate these assumptions as their company moves forward.

http://ecorner.stanford.edu/swf/player-ec.swf

If for any reason you don’t the the video here, the original is on ecorner.stanford.edu as Keep Testing Your Core Assumptions.