Very stupid, it gave away things like ride height data which is closely guarded.
He appeared to be showing that he lost a lot of time on the straights in comparison to Button, more so that the gap between their qualifying laps, due to using an old rear wing. However, Button pointed pointed out that Hamilton had more downforce and should have clawed time back in the middle sector. So he appears to have doubly shot himself in the foot.
I don't believe this story from Eddie Jordan about Lewis going to Mercedes. I think he would be mad to do so, he has a far better chance of winning the championship by staying with McLaren.