Update: it works for manual bets, but there are rarely any prices at 1.49, so assume this is all made up for SEO purposes.
"My new intern, Ben, has just written his first article. It can be found here:"
Ruminations Of A Donkey: Ben The Intern, Girl makes £100 a Day on Betfair
Just tried it, the costs are more than the winnings.
When over 1000 transactions an hour are made there's charge of £0.02 per manual transaction. Each trade is two transactions so the most you could earn is £5 per hour.