I'm no expert in these things, but I think it's safe to say that the session almost always goes on longer than the video that gets released.
Also, I think some producers have even offered their fans the opportunity of watching the videos get filmed. For example, you could pay the producer X-amount of money, and he would let you come to his studio to watch his latest video getting filmed. In regards to that, someone else on this forum once advised against that, saying that it would kill all your fantasies about those videos.
For example, the 'lee will be sweetly giggling while being tickled, then when it stops will be demanding a bottle of water and a smoke.
Or during a break, one of the models will mutter something like "What kind of perv would ever watch this crap?"
So I'd say it's safe to say that, whenever you enjoy a tickling video, you can bet there was a lot that went on that isn't in the clip.