As short as possible. If it takes more than 5 seconds to start seeing the product, I'll start skipping around or leave the site. You don't need a title sequence

As short as possible. If it takes more than 5 seconds to start seeing the product, I'll start skipping around or leave the site. You don't need a title sequence or intro music. Just start. Get to the point. Make the point. Then stop. Also, assume some viewers will have their sound muted. Assume some others will switch to another tab and only listen to it.