We’ve answered many of your questions about this video, see our follow-up here: https://www.youtube.com/watch?v=mif3_xoFOR8
Update, 10/3/16: Amazon just announced that incentivized reviews are now banned: http://reviewmeta.com/blog/amazon-bans-incentivized-reviews/
After analyzing over 18 million reviews, our data continues to support our claims that the reviews with an incentive disclaimer (eg. “I received this product for free or at a discount in exchange for my honest and unbiased review”) are much more likely to be positive than reviewers who did not receive a discount.
Here’s our original blog post: http://reviewmeta.com/blog/analysis-of-7-million-amazon-reviews-customers-who-receive-free-or-discounted-item-much-more-likely-to-write-positive-review/