Youtubers make huge amounts from paid promotions. In some cases its just a free item like a computer or tv or some other big ticket item, in other cases its a trip, or resort, or car loan, or early product access.

Something of value. In many cases, cash is paid based on views and sales through affiliate links.

In return, they are expected to give a glowing review of the item. They can leverage sales and its worth a lot to a vendor to get a good review of a tuber with a large sub base.

In most cases, the vendors get to see the vids and request changes before posting.

These promos can be wirth hundreds of thousands. This isnt pocket change.

So a lot of youtubers will whore themselves out and pimp products. Yt attempts to warn viewers with mandatory disclosures.

It is flagrant nonetheless. Scammers and barkers in a lot of cases.

Paid endorsements and testimonials must be disclosed as such.

EDIT: Google/YouTube rules also explicitly require clear disclosure of any material relationship with the sponsor.