No no no no. It's not about very little weight and a ton of reps. It's about lower weight (80% of what you would normally do for strength building) and more SETS. Also, I've pointed out numerous times, this isn't me going against the world, it's me simply quoting the National Strength Training and Conditioning Association's (NSCA's) stance on bodybuilding.
So, let's say what you normally do is 3x10 @ 25lbs. For bodybuilding, you'd want to be closer to 15x10 @ 20 lbs, for example, or whatever weight you can handle for 15 sets. When you reach muscle failure through endurance lifting, you experience more hypertrophy (bigger muscles = more muscle endurance) than strength building (because you're not really taxing your muscles weight wise). So the goal is to overtax your muscles as usual, but over a longer period of time.
You will still be building strength, but not as much as if you were to do a 3x6 @ 30 lbs routine, for example, which would build up strength faster but at the cost of less growth.
It really depends on how far you want to go with it, but the NSCA says that it's not uncommon for bodybuilders to try and make their way through 20 sets for a particular muscle group.