I think he's jerking your chain cause it's been documented all over the net. Here's a quote taken from the gold refining forum.
Per the research I've done, the film on hard drive platters contains platinum, for a 3.5" platter, there is about 1 gram of film, and the film will contain between 10% and 35% platinum (more platinum the newer the drive). so 10 platters would be 1 gram or more.