London 2012: Sanya Richards-Ross on mystery illness and Christine Ohuruogo

American sprinter Sanya Richards-Ross is hopeful she finally has a proper diagnosis of an illness she has been suffering from since 2007.

Richards-Ross was initially diagnosed with Behcet's Disease but says she now believes that was incorrect.

The 27-year-old Jamaican-born 400m star also discusses her rivalry with Britain's Olympic champion Christine Ohuruogu, and the success of Jamaica's sprinters.