If I'm not mistaken, that's another Hagley & District autotest, on the same site as the Lotus (or Caterham) Seven display that's been on here.
Anyway, as an ex-Mini Autotester, let me assure you that the rear brakes definitely work. In fact, unless things have changed in recent years, by regulation they have to work. Dexterous use of the handbrake will cause the rear to lose traction and spin like that - weewillie has it right.