Dude f2p youtuber is close to a fraud, those builds don't actually work legend or platinum. Haven't you noticed how he/she only shows replays winning? Or how whenever he/she posts his/her KoG deck it is never a f2p version?
If you look closely, most of their winning replays are either they played 1st turn or their opponent didn't disrupt their 2nd turn plays (with Fiendish Chain, Floodgate, etc)