2 things, i was not happy with the way he connects the battery for a long time, the only reason i can think to do this is to shorten the time period the device is un-powered by the battery.The other thing was that he then placed the battery in series with the LED, this may well be to charge it, but if momentarily the battery and series led's have varying impedance of the inductor then the battery may end up introducing power to the system.