I googled it up and registered. The site says "free" video, but when I try to watch it says "there has to be money on yr account"????
Do you have to pay for it?
No but you need to have an account open. At the end of the day, it is a betting site and the Live Stream is there for the gamblers, not the tennis fans.
I happen to be a gambler myself so it isn't a problem for me but if you're not a gambler it's tough. You could just place a bet on say Federer to win his next match. Then, you could argue, you're not paying anything to get the stream just taking a small risk.
Just downlaod TVUPlayer and watch it on the Tennis Channel. I think Betfair only have a small resolution screen anyway.
I have it on Full Screen and the quality seems quite good.