Normally, memes are the furthest thing from funny, but they, combined with the music, made this so amusing to watch.
Nice vid. I agree with Los about the meme part. I usually have this problem too; I sprint just before the reload animation finishes and don't properly reload, causing me to have less ammo than I intended or none at all when entering a firefight. That and I get pwned when I sprint too much because I come out of sprint just that split second too late, and someone pops me just as I'm about to unload on them.