The consumer never gets the affiliate cut either way. If there are coupon codes, the consumer wins. If there aren't, the customer only loses a bit of privacy about what they're buying, which most people don't care about anyway.
the video explains how honey has the same thing but the cut they give you seems to be tiny - like less than a dollar to users for a $30 commission for them as one example.
i dont know if this is common practice or not but i'm not a user of these extensions personally.