Hmm...
For a first, this isn't bad aside from the graphic glitches at the end. Here's what I think...
Graphics: I really like the style that was used here, but the dinosaurs could have been animated better. I suggest that you study up on movement for a bit. Plus, at the end when the Predator was sinking into the ground; the ground layer wasn't in sync with the bottom of the stage, which was really jarring and you could have added an extra graphic layer at the very bottom to fix that.
Sound: I really liked the music in this so no problems here.
Content: It's original and it made me chuckle for a bit. Sure, it's simple, but not everything needs to be complex in order to be enjoyable. Plus, at least it has a small filesize.
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-Nice style
-Small filesize
-Good music
-Mildly amusing
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-The animation and comedic timing could have been done better.
Overall: Here's a seven from me.