Basically the guy wants to create a small turbine inside of his shower head that would spin and create a current powerful enough to run a LED.
Basically he wanted to create a DIY version of showerstar version
These fancy version would be possible if you had enough water pressure but it would be much cheaper and easier to use a Throwies. A disposable LED and Battery that lasts 2-3 weeks with a thick layer of silicone. Most of the parts can be bought for less then $1