If I 'm correct 7 x 5.5 (or so) is the ultimate female size preference. I think this is because its a length that hits deep but doesn't stab their stomach and the girth stuffs their pussies without ripping them,apart...
8 x 6 seems very alluring but bitches will be a lot more hesitant blowing you, or even getting fucked for that matter. I can also relate this too bodybuilding, its good to be big and strong, but its not exactly good to be that 200+ pound gorilla freak (no offense).
All my opinions are purely speculation though as I am still a virgin and lack first hand experience as to how bithces handle dick, but it makes sense to me...
And I can't see that video (no flash) so I cannot answer the original question...