2 years ago, betfair delayed every single one of their streams about 3/4 seconds, so bots with access to real-time scores had the edge, but people could still cancel their bets sometimes before being gubbed.
Today, they have pushed another change to livevideo, delaying their streams even more, around 10/12 seconds behind of real time action. The same week they are trying to push a change on tennis markets to 3 seconds delay instead of 5.
be aware they are moving again once more to anti-customer policies