I don't think iPlayer works outside of the UK as you have to be a licence-fee-payer to watch.
I'm sure there will be other streams available, if you search for "BBC ONE STREAM" you will probably find something.
Anthony Joshua is the massive favourite to win though, doubt JR will do very well as WSB aren't widely followed here in the UK. In fairness I haven't watched the last few years, I try to keep up with the WSB, but what with Motogp, BSB, Speedway, rugby, football, cricket (let's but go into that one), F1, boxing and darts, I struggle to find time. Oh and having a job and family, what an inconvenience.