At about the 23 second mark, Thibs makes the point of ‘shrugging’ your traps up. So some people actually teach this point.
From a personal perspective: Benching is my weakest move and my most technically poor exercise. But over the past couple of months i have really been focusing on how to create consistency within the movement. Here are a couple notes from that:
As i set up, i start at my feet placement. I have narrowed my stance and started the movement from my heels, as opposed to pulling my feet under me and arching from my toes. By starting from my heels with a narrower stance, i am able to solidify my base and generate more drive into my upper back. This helps me because i am a not short, and do not have great hip flexor and groin mobility, so i had no power from a wider base.
When i grip the bar, i start with my initial hand position at a close grip bench, index finger on the smooth part. At this grip position, i get my upper back tight, and can begin forcing my traps into the bench for proper position (contrary to the Thibs video above, i do not shrug. I try to get my scaps and pelvis as close together as possible, back and down). I then work my hand position to my bench grip from the inside out. This was the critical change, as i can maintain an ultra tight upper back without losing tension. When i tried to get tight by just gripping the bar regular from the onset, i could never get tight enough, and got splattered at the bottom. Working from inside out helped me maintain greater tightness as a unracked the bar, Inside out gripping immediatley led to better lifts and a greater consistency.