The dreaded elbow flare...just like the butt wink in the squat, except WAY. MORE. SERIOUS. Flaring your elbows early in your bench (uncontrollably) is a bad deal. Not only is it putting your shoulder in a compromising position, but you're sacrificing pounds.
What am I talking about?
[youtube=http://www.youtube.com/watch?v=ZP6daoDjNXc&feature=youtu.be]
Mark is working with 345 here, about 95% of his training max. You can see the first rep he does a nice job of keeping his elbows under the bar, keeping his lats engaged, and pressing through the rep. The second rep, however goes to shit. His elbows slide back (lats not engaged) and the pressing goes from his triceps to his front delts.
[youtube=http://www.youtube.com/watch?v=4021-UIxY9s]
A better example here, you can see Sarah flaring as soon as she presses off the floor. This is an immediate indicator that her front delts are stronger than her triceps as a likely result of bad patterning over time.
Why are you flaring early?
A) Poor technique
or
B) Weak triceps
or
C) Both
How do you fix it?
Three ways you can address the problem. #1 is a must.
#1 Direct tricep work - specifically the lower part of your tricep. That horseshoe isn't going to fix this problem. You need more meat around your elbow. Use any and all types of extensions to target that area.
1/4 dips and football bar ext are my favorite using both high and low rep ranges. But floor presses can be a big help for this as well because the shorter range of motion allows you too keep tension on your triceps through the entire movement.
#2 Use chains - they allow you to slowly load the movement, but you'll have to be aware of your technique. You can't use a weight or rep range that you start flaring early in, otherwise you're just engraining bad habits.
So start light, find a weight in the 3-5 rep range that challenges you to keep your technique perfect.
#3 Use tempo work - 3-5 second eccentrics with 3-5 second concentrics (tempo 3-0-3 or 5-0-5) with light weight to teach yourself how to fight against that flare. The goal being to keep tension in your lats and triceps through the whole range of motion.
Pick a light weight, move it with intention, keeping your lats engaged, elbows under the bar, and tension on your triceps. Burn baby, burn!