When I took my shodan test for Shotokan, I was performing Tekki Shodan, and on a press with one hand and inverted punch with the other, I wacked my elbow and my whole arm went a bit numb. During the same kata, it may have even been the same punch, I nearly got my fist caught in my gi top. However, when watching the video, I didn't notice either "problem." During my Sandan test in Shotokan, I performed Gankaku ("Crane on a Rock"), one of my favorite katas. Half-way through, my mind went blank, and for a split second I hesitated, but, once again, didn't notice it on the video.
On the other hand....it is fun to sit around with all those who tested and make fun of...I mean, constructively critique everyone's performance.