I agree that there aren't enough full-body animations in the reel. The strongest clip is the robot at the end. The heavy gunner has potential, but you can squash and stretch him a lot more to emphasize how heavy his gun is.
I hear my animator friends stress over "weight" over and over again. Here's a demoreel they think demonstrates the feel of gravity very well: http://www.tjphan.com/html/animation.html
In their words, things like "key pose" and "pacing" both help tremendously with weight.
Hope this helps!