Oh, here's a couple more:
Solar Hot Water Design:
I'm putting up my own solar hot water system, as is a friend of mine. Easy enough to film that and what we learned from the DIY aspect of it.
Rockets Stoves!
I built my own
rocket grill. I know a couple other people who have done them as well. I could make a video showing how to build various types, construction tips, theory of operation, etc.
Graywater laundry system.
I save about $45 a month on my water bill by flushing my toilet with used laundry water. Think of it as a "suds-saver system". I would show how anyone could build such a system. It's really not that complicated. Maybe that could be combined on a single video with other water-conservation projects or even with rocket stoves as a "DIY Home Projects" video.