These guys pretend they don't get "paid" by Sony. But they get all the gear they want from them, newly released gear to review, lenses to test/sample, in exchange for positive reviews. They might not be told to write a positive review, but good luck getting more gear if you trash them.
Sony knows who to send gear to, because they know these youtubers are desperate to continue to receive gear to review.
Sony gear videos get higher views on youtube so its the brand they want to continue to pimp.
So yes they might not be "paid" by sony, but by getting all this gear to test and review from sony for free, it saves the reviewers thousands of dollars. Youtubers are the new age used car salesman.