Here's a great example of starting in the wrong place. The video below is queued up to start at 1:44. Just click the play button and enjoy. But then rewind back to the beginning, and see how much time they wasted. Imagine how many people quit watching before the demo started!
What's the solution? Split your message up into smaller chunks, and lead off with your biggest splash. In this case, imagine a 90-second demo that started with the machine laying the bricks, then other videos linked at the end for Safety, ROI, etc,