While I won't dispute that this hitmarker appears dead center on his core, there is another factor to consider.  You just jumped off a ledge, and you can see your player's knees buckling and recovering from the drop.  Until he's fully recovered from the fall, I think his accuracy would be less than it would be on a stationary shot.  Perhaps this caused fewer pellets to land?

It seems most of the complaints relate more to lag than an actual problem with the game code for the shotguns.  I have very few complaints about lag (lucky me?), and I get fairly consitent shotgun performance.  Sure, I get hitmarkers like everyone else, but there is usually a reason for them. 

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Most of the clips people post demonstrating the inconsistencies show inconsistencies in aiming more than anything.  I always pause the clip when the hitmarker first appears, and it's usually centered around an elbow, or the tip of some of extremity.  I would expect a hitmarker on the edge of the hitbox will have at least half the pellets missing, not to mention some percentage of the pellets going over or under.  This would mean only a couple would actually do damage.

Your clip is different from those because your hitmarker is dead center.  Had you not taken that fall just prior (it seems longer because you slowed it down in your video), I would question it.  I was just pointing out that there is another factor.

I'm almost certain that a fall would affect accuracy until the player recovers.  Similar to how taking a sniper shot while moving will usually yield a less accurate shot than a stationary one.  Since we can't say for sure, I'm leaning on that uncertainty.  Perhaps Dead Silence elimates damage (red screen), but has no effect on fall recovery in terms of accuracy?  We won't know until someone from IW chimes in (I won'thold my breath) with facts.

This late in game, I wouldn't expect any changes.  What you have is what you'll have to live with.  Fortunately for me, shotguns are still fun and any inconsistencies are usually related to other factors besides weak code.

I don't have an explanation for that clip.  At that range, your shot appears to have been good enough for the kill.  Seemingly unnecessary hitmarkers occur with other weapons as well, but as had been said, the slow reload of the pumps is definitely its weakness.  There is no time for recovery, even to a hipfired AR in this situation.

Do you recall if you had Quickdraw on that class?

I have only ever put quick draw on my lmg class. 

Look at 10:00 http://m.youtube.com/watch?v=0jVg1BTEZUI