Has Science Been Misleading Us?

I was messing around today on Youtube, and came across one of the many videos purporting to show an example of a perpetual motion machine. What's a perpetual motion machine you ask? It's supposed to be a machine, usually mechanical in nature that once set into motion, does stop and generates more energy than it requires to stay in motion. Science, and shows like Mythbusters has been debunking these perpetual motion machines for years. The hope is that someday someone will come up with a machine that generates more electricity than it consumes, thereby giving the world abundant, free, or really cheap energy.

My thought on this subject is, has science been misleading us into not asking the right questions? Why does a machine have to be a "perpetual" motion machine to give us benefits? Why couldn't someone just invent a machine that once set into motion might just run on it's own inertia for say a month or two, generating electricity until it finally winds down and needs to be started up once again? That's how an old fashioned spring-wound clock operates. You wind up the spring and the tension on the spring keeps the hands moving for days or weeks at a time, depending on the size of the spring.

Let's say you had to use an electric powered motor to start a large flywheel turning and after an hour you turn off the motor and the flywheel keeps turning through it's own inertia for a month through a system of cleverly balanced weights. That flywheel in turn spins a large alternator that generates electricity. As long as you're generating more electricity than it took to get the flywheel going in the first place, I would see that as being a great scenario without it having to be perpetual. Maybe we need to stop thinking that something has to run on it's own inertia forever and just find a way to harness what I'll term, the "temporary motion machine".