Unless there's a quirk in the spin characteristics (as with the Tipsy Nipper in the video), a flat spin is an
intentional spin mode, and is driven by out-spin aileron combined with the gyroscopic effects of the propellor under significant power...plus propblast over the elevator. Most airplanes with neutral and normal spin characteristics will NOT go flat on their own with power off. There's nothing any more "risky" doing an intentional flat spin vs. a normal spin in airplanes that have normal spin characteristics. Various aerobatic airplanes do them safely all the time. I do them in the Pitts, and can recover in less than a half turn with power left on, plus the correct inputs.
But never leave power on in an emergency spin recovery situation! But aerobatic airplanes are designed with neutral characteristics, and large, effective control surfaces.
But in non-aerobatic airplanes, I would never try to produce a flat-spin intentionally. Some (non-aerobatic) airplanes can tend to go flat on their own after a certain number of rotations, if allowed. For airplanes that may go flat on their own - there are no generalized assumptions you can make about behavior or recovery of the flat spin unless this has been tested and documented by the designer. Ha...show me a POH for a
non-aerobatic airplane that describes
flat spin recovery procedures.
I do flat spins upright and inverted without a second thought in my Pitts, but I sure wouldn't try one in a Mooney or Cirrus...not that you should intentionally do any type of spin in those. I wouldn't even try a flat spin in a 172. And furthermore, the high power setting imparts a lot of gyroscopic load on the crank flange, which non-aerobatic cranks are not designed for.
Auto flat spins can be a problem due to the fact that the airplane's relative airflow is almost perpendicular to the fuselage. With little forward airflow over the tail, the rudder and elevator become very ineffective. This is why you'll never see an airshow pilot recover a flat spin power off. Power helps with control authority. But power should never be used in any type of
emergency spin recovery, since it can make things worse or delay recovery if your airplane does not have these neutral spin characteristics and/or your recovery inputs are not quite perfect.
The pilot in the video finally stumbled upon the right control inputs for flat spin recovery...in-spin aileron. If the approach to landing looked like he was drunk, it's because he was...sorta. After that many turns his inner ear was screwed up and he had significant vertigo and dizziness. I credit him for not giving up and continuing to try different things. Moral of the story...understand your airplane's spin characteristics before you intentionally spin it. If you don't know, prepare to be a test pilot! And of course get good spin training too!