I know you want the action to be quick, even quicker than the human eye... At the same time, (and maybe a frame-rate issue) things get a little... over-spaced if you can follow my meaning. When the characters would reverse positions (a basic strategic move) for fluidity, I might suggest you work them a little closer together for the fluidity. Let them separate naturally... The flashy screen and suddenly they're opposite from where they started is a little old and used up.
On the whole, I think you still got it. Might be kind of like riding a bike, once you get it, you might get rusty and awkward, but you don't lose it. You have a talent, and I'm not going to beat it up on a lack of story or drama or... (we can just say blah-blah-blah) You get the point, and I know it's just a demo.
The art work was clean, sounds were on time, and everything seemed crisp and smooth for the most part. I think a little polish (even a spit shine might do...lol) and you could stick together a storyline and run with it.