Here's my take on it:
For an arm-only break, that's pretty powerful. That's all stroke. I bet that break is up around 19-20mph as is. A lot of people can't hit the balls that hard even though they're throwing their body at it.
Once he gets body into it, it will be much more powerful. But he also says this is just 75%. If he gets some of that Bryant, Busta et al type of body action going - it will be huge.
But it takes a lot of time and work to learn to put that much body into a break AND be accurate. Meaning, good hit on 1 ball and proper hit on CB for CB control.
The modern power break goes contrary to what you are taught to do for a regular shot. We absolutely try to minimize all body movement when shooting, but in breaks - body movement is desired. That's why the break shot is the toughest. Stroking that cue straight and getting a precise hit on the cueball is tough when there's that much body movement going on. Not to mention, so many large muscles all firing off at high speed.
A lot of people push the power-break at all costs view point. I disagree. I say work your way up in a controlled manner. Control is huge. Proof that it is more important than all out power is the existence of soft and medium breaks. Meaning that there's a lot more to making balls than just all out power.
The guys that string racks all have one thing in common - and it's not complete and total super-power breaking. It's the ability to make a ball very often (and that is due to a variety of factors, knowledge and technique) and controlling the rock.
Therefore, there are two goals to a break:
1. Make a ball
2. Control CB
And #2 is almost nearly as important as #1. We have to give the edge in importance to making a ball because without that, you're back in the chair. That said, it's preferable to stay at the table even without a good shot or no shot at all. When at the table, you can always make something happen. Nothing happens in the chair.
But a lot of people make a big mistake getting fixated on what I just said. In reality and practicality, CB control is nearly it's equal because at the higher level, not controlling the CB catches up with you. In other words, it shuts down run outs and when you aren't generating a high enough percentage of run outs from your break - you will not be able to compete. In effect, it makes making a ball on the break nearly moot. That is what separates top pros from semi-pros. Tops pros get out more and that all begins with the break. They have that centrally located cueball that instantly leads to a higher percentage of good opening shot. That means getting and staying in line. That means less push out and safety battles. That means more winning.
Power/speed is merely a component of the greater goal of making a ball. There's more to it. If a pro is smashing the rack at 25.5 and not getting results, sometimes they turn it down to the 20-21mph range and start making a ball. There's rack analysis. CB position and a lot, lot more.
Therefore, making a ball is a goal - speed/power is a tool or device that can be used to achieve that goal. The goal is higher than the tool.
Shouldn't make a tool/device in your game the goal. That's what a lot of players fall into. The quest for generating speed at the cost of other considerations such as control.