Chartboost

So I am trying chartboost for my game I am currently working on. Now I could use some help of someone who has worked with it. I use it for rewarded video ads. And it works wich is nice. But I have a feeling I am doing it wrong(could be wrong tough;)).

So I have 4 campaigns for the ad. Highest priority->high prior->medium->low

So I edited the bulk bid to 5->4->2->1 . I could not find much about this subject on the internet don't even know what this means really...

So my questions. What are bulk bid? and how does it make me money?

What is the best setup for bulk bids?

Thanks for any help:)

Bump. I can't seem to find the answer on the internet anywhere..

Also do I only get some money when people click on the ad or also when they watch it?