what you see a lot of in streetfighting is headbutts and kicking folks on the ground , frankly a lot of martial arts aren't really suited to real fighting
Are you trying to say that headbutts and kicking folks on the ground aren't a part of martial arts? Because if you are, then you need to get out of your gymnasium.
FWIW, I show these hidden gems in kata all the time. Then I show folks how they leave themselves open for such kinds of attacks when/if they do certain dumb things. Most good (experienced) martial artist teachers do that. And many martial arts styles have these basics covered. It's simply a matter of execution on the part of the teacher who conveys the style to students.
Several decades ago in a dan test at Bob Bethoney's dojo, one of my students did a (pulled) head butt in his test sparring match. Bobby was officiating, and said "No head butts!" No problem... we can adjust to whatever the rules are. However... next year before the dan test sparring, Bobby announced that head butts would be allowed.
just look at the clip, what stance would you get into?
Without even looking at the clip, I can tell you that most any way you stand (or position yourself on your knees or supine) is a stance. The key isn't so much the particular stance you are in, but how well you handle your center, your mobility, your weapons, and your defenses while in it. That - and not specific stances - is the essence of good martial arts.
Whether or not you succeed is another story. That's a function of many factors. If the odds are stacked against you, well the odds are stacked against you. But that doesn't mean you do the deer-in-the-headlamps thing and give up. It's your prerogative to maximize the odds in your favor - no matter how bad the situation is.
.how would you work in the back-spin kicks
In your TKD sparring classes where they belong.
However the fundamental element in this fancy high kick - a leg hooking motion w/o spin - is a fantastic technique that everyone should have in their arsenal. It works very well below the waist. It also is a simple tool used by grapplers while on the ground. And that requires no special distance or warm-up.
what about the "Flinch Responce"
What about it? It's there, Ray, whether you want to recognize it or not. It doesn't have to be a confounding factor. On the contrary, most good martial styles have flinch responses embedded in their movements.
Your lower brain responses will want to act before your training kicks in. The key to training is knowing what those lower brain responses are in myriad situations, and then learning how to weave your training responses in to what your body naturally will do before you can consciously evaluate a situation. And if that doesn't make sense to you right away, then sleep on it and ask around.