I was thinking about this betting sites... it's atually a great way to transfer funds to cash without taxes.
Unfortunately it will not work, because sometimes you will win at DirectBet, and other times you will win at the cash book, and eventually in the long run it will even out.
You can increase the chance of succeeding on a single or few occasions by taking the big favorites in the cash book and backing up the big underdogs at DirectBet, or martingale your DirectBet wins, but it will not change the long term outcome, if you do it enough times, it will eventually even out.