Mambobaas, did you stop to think why all those people were speeding in their cars and breaking the law? It is because speeding is condoned by the authorities however much they may claim to deny it. A motorway cop won't bother with a speeding vehicle until it is over 85 mph (unless it is really blatant) and many magistrates courts regard speeding on a motorway as a far lesser crime than in built up areas. If the law were to be rigidly enforced then the roads in UK would come to a complete standstill (OK more of a standstill than they already are).
My point is that if you condone or approve of this guys stunt under the bridge then don't be surprised when it happens again and again until someone spears in doing it, killing himself and several onlookers and we all cry "How could this sort of flying indiscipline be allowed, what have the CAA been doing about it".
What the guy did wasn't difficult - a confined area requires more piloting skills - but it was illegal and ill advised and if and when he gets caught he has only himself to blame.
If he gets away with it then what might he try next?