This is a fantastic idea. More and more people are going online to find and research the products and services they buy offline, so this gives them a powerful tool to educate their prospects. Plus, it's available 24/7 and it doesn't cost them a thing to have someone watch the video, freeing them up to focus on other areas of their business. This is a great example of employing 'systems'.
The only suggestions I would make on the video would be to include their website at the beginning and end of the video. If they don't have a website, shame on them.
Also, I'd present an introductory offer to anyone that calls or contacts them and mentions the video. Maybe 10% off or 10ft. of concrete curbing free.
Again, this is a great use of available technology, and they might as well use it to it's fullest potential.
It might be just a bit long as is. People lose interest easily and there really isn't anything to hold the viewers. Unless of course it's someone that's fascinated with concrete curbing.
I agree that a narrator or voice over would be nice. Or even better, talk about the benefits of concrete curbing. The finished product looks fantastic and it's an interesting process, but there really isn't anything to motivate a viewer to pick up the phone and call.