Here are three websites that use an autoplay video above-the-fold to tell their stories visually:

• Icon Aircraft
• High Point University
• GlowForge

In all three cases, note how:

1. You learn important points about the product almost instantly, without words. For example, with Icon Aircraft you learn that the plane can land in water, and also works at a normal airport, and can be folded onto a trailer for easy towing
2. It is an extremely inviting, no-effort way for a visitor to learn about the product. No reading and no mental effort is required.
3. A call-to-action button is an obvious thing for the user to click