Defleaing your dog?

I haven't tried this yet but was told you could buy advanced 12 month tree and shrub insect control concentrate. Its a liquid, you put this down the back to the tail of your dog, and its great for fleas. I just wondered if it would harm the animal. It has the active ingredient Imidacloprid 1.47%, the same chemical the vet sales trade name advantage,but its more dilute then it but way cheaper.This guy swears by it and hasen't had fleas in over a year. I can give you his website. He has hunting dogs. I just don't want to harm mine.