What Was Paul Signalling?

The Beatles appeared before a huge audience in Liverpool for the premiere of A Hard Day's Night on July 10, 1964.  They went out on a balcony to wave to the crowd.  Watch the video at http://www.youtube.com/watch?v=lI6LAQB5b58.  At 3:20 and 4:06, Paul gives a thumbs up signal to the crowd.  At 3:09 and 3:53, Paul crosses his arms with his thumbs up and at 4:13 he crosses his wrists with his thumbs up.  I was reading a book, Underwater Swimming by George F. Brookes and Robert B. Matkin, in collaboration with the British Sub-aqua Club (1962) and the symbol for "wash out"--cease diving and return on the surface--made by the surface party lookout to underwater divers is that signal.  Again, it could be a clue that Paul was aware, or was learning, deep-sea diving.