When I first saw the Tongariro roll cast, I thought to myself what a violent cast......
Much later after learning to Perry Poke and understanding the mechanics behind the cast, I re-visited the Togariro roll cast with better appreciation on the rational behind the cast. Here is another video by Andrew Blake with the cast done more err....gently?
The Tongariro roll cast (TRC) is essentially a Perry Poke or vice versa (don't ask me which came first). With the TRC, the poke is done with rod tip very close to the water, minimizing airborne time of the line, allowing water to grab the line sooner for the back cast. This way, the back cast can start almost immediately after the poke. In contrast, a Perry Poke will have the fly line airborne longer as it drops to the water and there is a perceptible wait before the caster can commence the back cast. So, essentially the TRC is quicker to fire off and if you have a heavy fast sinking nymph at the end of your leader, that is a big advantage.
Here is a video on the standard Perry Poke where the fly line stays longer up in the air before touch down. The caster is forced to wait a bit before commencing the back cast. Not a bad thing if you want to allow the anchor to set.