I'm getting the same knocking noise after 1500 miles (Professionally Built-up Look 595 with Campy Record 11speed) during race speed sprints (usually near end of a sprint and when the bike is rocking side to side). No other time I'm I hearing this knock including standing climbs. I'm 180Ib all-arounder but sprinting is my strongest skill. Squeezing the non-drive side crankarm towards the drive side, I was able to make the whole driveside crankset move back and forth, I could see the drive side of the crankset move out or away from the bottom bracket just like your pics!! My mechanic/builder is checking with Campy....so stay tuned.