You give a product to them for free and they will advertise it.
We have some clients with over 10,000,000 youtube subscribers. That means every time they receive a free item they promote it,
And up to 10,000,000 subscribers get notified a a new clip. And the majority will watch it.
We have people who advertise certain niches and some who you could call "socialites" who have large twitter and instagram followers. So every time they are seen in new clothes or have a new hand bag. 1000's ask where she got it and she politely post a link.
Our client are not typical advertisers. They just show off their product, or show how it works. And this draws in more revenue and likes then an annoying pop up ad. People actually sit down and listen and watch my clients promote.
1 gig is worth $5.00 but you must offer your item for free to the promoters. The more free offering, the more advertisers working for you.That is how it works. They will not advertise things they have not used. People with huge following have to appear they are not advertising. You must give time for reviewers to use your product.