Nice.
The only advice I got for you is to never stop animating; like any art, you become even better with practice...so that should clear up any doubts you have for yourself in your drawing ability.
Onto the criticism:
(Pros +, Cons -)
+The music was epic and well chosen!
(Not a con, but I would suggest finding an abundance of sound effects NOW for future projects...audio other than just the music is encouraged. Even in some music videos they'll add other sounds or voice-tracks to match what's going on in the video.)
+You have a keen attention to detail, and the character designs were proportional!
-Cheesy anime elements killed the mood in certain scenes. Generic Crew Member #5 studies his screen with the calm eye-darting of a gamer, and although he's reacting to bad news coming up on the readings, literally shivers like he just shat his pants, and spins around, maw agape like he's either shrieking like a monkey, or ready to inhale a grapefruit.
...What did he see on the screen to make him react in such a way? Obviously the audience isn't supposed to know to provide a hook, but whatever it is, with a mouth open in such a way like that, it's not like he's going "Commander! Independence Day is happening at the Church!" or not even so much as an open-closed-open, "OH SHI-" ...he just see's the screen, shakes like Michael J. Fox, and turns to apparently scream at the top of his lungs.
"AAHHHHHHHHHHH!!!!!"
"Oh for the love of- WHAT THE HELL IS IT, Generic Crew Member #5!?"
"...There's some aliens attacking on the screen...they're big, and they're probably going to beam down a couple of their troops to start cappin' civilians."
"There...wasn't that easier than just screaming at us all?"
"I get excited!"
-It's not a huge con, but I'd recommend not outlining fluids and liquids in black. Say if it's gushing blood, outline it in a darker shade of red...Light blue tears? Outline it in slightly darker or slightly lighter blue. White beam? Some hue of gray. Y'know what I mean?
-Also there was a scene in there when Captain Cowlick saved the girl, tumbling out of the way of an oncoming death beam. While the alien promptly refuses to keep shooting at them a little to the left, we see the Captain LIFT HER THE FUCK OFF OF HER like she was nothing to check to see if she's okay.
I understood what was going on...he saves her, and he wants to look her right in the eye, and check to see if she's safe. But a slight lift, where gravity still comes into play would be sufficient...He grabs her by the shoulders, does what I would liken to an upside-down pushup, and LIFTS HER parallel to him like she weighed lighter than Styrofoam.
...Hey, you asked for reviews, you got 'em. I still enjoyed the flash. And for your second ever, it's REALLY DAMN GOOD.
To gain complexity in future animations, be sure that if the buildings are shaded, shade the trees and street lights too to give it that added detail. When the scene is on the face, have the eyelids narrow and widen accordingly with face as it studies the screen...Like, seriously, just watch different people's faces and notice subtle movements in the eyebrows, eyelids, cheeks, lips, and especially head-position...if you can master realistic body movements at an early age, you'll jump so high in your animation ability, your nose would bleed.
Again, I can't stress this enough, keep doing what you do. Just keep it at a steady pace of outdoing yourself constantly...
...So this flash was better than your last one...your NEXT one should be better than this!