Okay, for one, that's not the Bob Anderson they're talking about because supposedly this guy lived to be 90 and died recently. The one you linked me died in 2008.
This is the guy you want:
He's just a stunt double, not an actor. Stunt doubles deserve credit and it's pretty badass that he got to be a stunt double for Vader, however he's not the actor.
You people below....don't know Jack. I don't think it would help if I set you straight at this time. All this info was not exactly kept a secret. It's been ongoing for over 30 years now. Bob Anderson was the Sword-Master. He actually filled in on a lot of the dueling scenes. He had screen credits for many many movies, being the number one sword-guy in the world for decades.
David Prowse was the main man behind the mask.
Bob Anderson portrayed Vader during the intense lightsaber fight scenes in Episode V & VI.
Sebastion Shaw was Vader when he took of his mask in Episode VI.
James Earl Jones ("the black dude") was the voice actor, never in the suit.
Atleast look up things before you throw them out on the interwebz.
So this Bob Anderson, in My book, is not really THE Darth Vader.