Nice vid post.
Now, you can spin while running full speed, but what you get is a very small window for which to spin so it's super super tight and you wind up just spinning slowly while continuing to move forward. If you try to increase the curve of your spin, you often times wind up losing your balance and stumbling, that's why we see ball carriers instead slow down and try to make a juke at that point. The only man I know that could to a degree defy that was Barry Sanders, but I'm still not sure he was really even from Earth, lol...
Adding the steps directly to the spin animation would more than likely handcuff you. However, putting the steps in as a separate move to gain control of the back allowing you to set up and do another move might be a very realistic chaining of sorts. Like, you're running full speed up field, you're one on one with a defender, you press something to slow down with those quick steps then you press something else to perform your next move at the end of the slowdown-step animation.
With all that said, a form of this has been tried before this generation except it didn't make you dependent on having to stop and gain your center of balance; it was used as a juke move instead of a slow down/set up action. I bring up Madden 07 again, because just today I saw a move where Westbrook was running full speed, he slowed down and came to a complete stop, the animation finished and he then made a spin. The difference between what Westbrook did in Madden and what we see in real life, is that in Madden Westbrook just halted cold with very little effects from the momentum (i.e. his steps while quick were too controlled and didn't look as affected by momentum as running full speed--or even half speed--would normally cause), whereas in the video you posted the ballcarrier made quick but very pronounced steps to gain control and then make a strong spin.
Okay, I said an awful lot here so let me summarize, lol...
-To make a quick, super tight spin that still moves you forward at any speed (but usually running full speed), that should still be available. But once you commit to that spin you shouldn't be able to do anything until it finishes, and UNLESS a defender makes contact and you are able to then make a move off the hit.
-But to make a
controlled spin/juke that allows you to move in any direction you want to spin/juke, you should first have to press a command that makes you stop and take quick steps to gain control, and then press another command (plus using of course the left stick for direction) to spin or juke in the direction you want.