Jeff Gellman at Solid K9 Training has a lot of great videos on Youtube, Facebook, and Periscope.
What's interesting about this video is what a clearly blank slate he is working with -- not with the dog, but with the people who run this shelter.
This is far too common -- good folks who love dogs and have "been around" dogs may be OK right up to the moment they have to deal with a big, heavy, adult dog who is the very epitome of "self-will run riot".
There is not a bad bone in this dog's body, but he is NOT going to be trained with cookies, "ignore it," and body turning alone. This dog is started off with the wrong collar and the wrong level of energy, and given both the wrong reward and the wrong consequences. The result is that this dog spent months in a cage, when he could have been our learning and adopted.
Jeff saved this dog's life. He does that a lot. Check him out.