Cool
This is a pretty sweet piece of work, and it is seen that you've got some talent, and if you'd like, I'll go ahead and offer some criticism now. ;)
First off, the comedic (and you may or may have not intended for it to be funny) timing is brilliant. This is a major part of general movie making a lot of people miss out on, and I can tell you played around with your scenes before presenting. The idea is that you keep a scene lively and don't overwhelm the viewer with too many damn images to process in a short amount of time, and the way you do this is with cuts. Very amiable. Don't lose that.
But that brings me to one of my gripes with the animation: the cuts! Why do you you need to cut? Well, to be honest, the animation is stiff and tweeny. I did notice you sampled some good old fashioned FBF a couple of times, but I would dearly like to see more of it. That is the other big part of comedic timing, it's not just cuts to stimulate the brain repeatedly with different images; remember that some of the greatest animations have little to no cuts. It sounds like a daunting task to put so much attention to minute things, but if you can motivate yourself you'll have a well-rounded, complete package.
Now what is the best way to improve your animations overall, dis-regarding everything I've just said? Well, practice, practice, practice! Work on your art, FBF, and everything. If your serious about this stuff, get yourself a Wacom drawing tablet. It's especially useful if you can draw IRL.
Now I liked a lot of the perspective you had going on with geometric objects, and that was cool, but some of the background art and hand-drawn stuff seemed lifeless. Think that space scene with the ship at the beginning. You should work on developing things like that a little more.
Perhaps we've gone a little far by over-examining Moplar the Alien, but I sure hope this helps. :D
---GRAPHICS
Cool, sometimes polished, but in general a little bland.
---SOUND
You used some really great sounds here, but I noticed they had a very high-pitched static sound that played along with them. That happens a lot, and it's really just Flash being a bitch. Try playing around with the audio quality setting under Publish Settings and re-export the animation.
---PLOT
I talked about comedic timing. The animation's too short to really go into detail here.
---OVERALL
Real nice! I look forward to seeing more from you. You have a TON of potential, and don't forget it. :)