OK.... perhaps I've been a bit too moralistic with my previous comments about "cheating".
But I still don't understand how the "system" can work... for example, you are sitting in the front row of the stadium... Federer is 40-30 up on his serve against Nadal. Federer serves an "ace" to win the game..... first you have to wait say 2 seconds to make sure there's no appeal by Nadal against the point.... then say another 2 to 3 seconds to place your bet (either back Federer, or lay Nadal, depending on the odds and the liquidity). Then, there is a waiting period imposed by
Betfair of (say) 5 seconds. That means a total of (at least) 10 seconds between Federer serving the ace and
Betfair accepting your bet. Surely
Betfair's communication system is faster than 10 seconds, and the market will have been "suspended" ???
...... or perhaps I'm missing some technological issue, and talking through my ar*e as usual.