If you cut the flow from your hose back by 70% it won't move the dirt in your driveway as far.
The point was, the water spreads out and slows down once it is no longer constrained into the same size as the nozzle.
Modern toilets dump nearly their entire flush volume in seconds. On my 1.6g Toto, the time between the flush valve opening, and it slamming shut is about 2-seconds. With a 3" diameter plug of water going down, the stuff should surf quite well. It's hard to say unequivocally with the flushmate, but it sounds like it is open about the same 2-seconds (and the one in the video is a 1.1g), meaning, it dumps its entire load in about the same timeframe. The difference is the velocity of the siphon jet, but that's only part of the story, as the diameter of that is fairly small compared to the main outlet of the toilet, which, again, is fairly small compared to the diameter of the drainage pipe. On a well-designed gravity flush toilet with a 3" flush valve, you'll get about the same surfing of the waste down the pipe as you will from a pressure assisted one without the extra noise, shredded paper, and repair costs. Again, not all toilets are created equal. The advantage a pressure assisted toilet has is that because the siphon jet is going faster, it can potentially break apart some harder wastes that the slightly slower gravity fed one can't. That speed is gone by the time it reaches the main pipe.
Take an old 5-6g or more flush toilet...time the flush cycle. MUCH slower exit from the bowl, so the surfing effect isn't as effective. Because there is more water, it can float things further, but most of the time, it takes subsequent flushes to move it along unless there's a significant vertical drop to speed things along. IF your pipes back up, it's likely that the slope is improper, and if things always stop at the same point, that section may be level verses sloped. Since the camera didn't see pooling water, it doesn't have a belly, but that does not rule out a flat spot, which quells much of the momentum.