Heyoop mate. Really good effort. Better than stuff I did at University!
First of all, it's very dark. Did you use linear workflow? You should look that up, if not. It'll help.
I'd expect to hear more background noise, it's cheap to add and would give you more of a war-zone feel.
From a staging perspective, it's a little hard to tell where the characters are in relation to one another. You could have used a wider, establishing shot to start with and set out the players and the set. It's not clear if there's two alien enemies, or if you've cut in time but stayed with the same alien. It's not clear where the crawling alien is, what spatial relationship he bears to the hero characters, and therefore what danger he's putting them in. I'd have introduced the weapon earlier, as the aliens don't look like they pose any danger.
The voices are distracting - not a knock on your voice, it's as much that without a decent audio mix they don't sound like they're part of the scene. Unless it was a submission requirement, you could have left them out and heightened the drama with hand signals.
Animation-wise, one thing to watch for is locked holds on both characters and cameras. When you have to be keyframe-efficient to get something done quickly, a camera is a very easy thing to add ambient motion to, and reduces the impact of "locked" characters. Also breaking up the animation, even if you keep the locks, so that not every part of the body locks at once, is a good idea when trying to work quickly and efficiently. You're missing breakdowns too, like when he turns his head and says he needs to change position, that looks like a straight slide across one axis (the turn axis, usually y), so it needs at least one other axis involved, usually x or the "nod" axis with a breakdown - see the Richard Williams' head turn examples. I'd involve all three axes and then break their timings up. Watch out for the alien's knee as he jumps, too, it breaks. You need a pole vector or leg roll control to keep that in check.
I hope that helps man, tried to be as constructive as possible! All the best.