Some decent quality, fan-filmed footage of black metal legend King Diamond performing at the Hellfest in France on Friday has been posted online and can be viewed below.  The former Mercyful Fate frontman recently made his return to the stage after recovering from an open-heart, triple-bypass surgery which he underwent in November 2010.  Since the surgery, he has quit smoking, changed his diet, and has implemented a regular excercise routine, according to his wife Livia Zita.