It's not clear how well this would scale up, but 40 milliwatts for household use is pretty small - in fact, it's tiny. As he shows, you can power a LED, or a clock, and maybe even a radio, but when you get beyond that you have to start thinking of some way to store the energy so that you can release it in larger amounts. You could put a bunch of these on a house, but you'd need 25 of these to get a single watt. So to light a 60 watt light bulb you'd need 1,500 of these generators.
Alternately, the household could convert to LED lighting but that adds cost to the system solution. Even with LEDs you'd need a bunch of these things to provide any significant lighting (one LED doesn't provide that much light).
And even then, you'd probably need to gather the energy during the day and store it in batteries so that you could use it at night - and when there's no wind. The cost of the batteries, and the maintenance of the battery system might make it a difficult solution for third world countries.
Mike