Is it possible to transfer money from one account to another?

I've been told that Betfair will call you and tell you they will close your account if you do it again, as it looks like money laundering, so don't even bother figuring out how to do it.

Is it possible?

Sure it is , just find a quiet market your mate lays 1.01 or whatever on some outsider and you back it.

Is it worth the hassle?

Nope , not only do you have to worry about betfair having a word in your ear  you also run the risk of a bot/or betfairs x-matching piggybacking your mates bet and you end up with a very poor bet and your mate nothing. Plus why would you want to give Betfair 5% for nothing, in these days of online banking it's easy enough to transfer cash either direct to your mate or his account without risks or wasting money.

^^
both correct , absolutely don't do it