"These kinds of payments aren't inherently suspect in and of themselves. If the video makers disclosed that Microsoft was paying extra for these videos, and if they were allowed to say whatever they wanted in those videos, then the whole thing could be seen as merely an unorthodox way to increase exposure for the Xbox One on YouTube.
That's not the case, however. According to a leaked copy of the full legal agreement behind the promotion, video creators "may not say anything negative or disparaging about Machinima, Xbox One, or any of its Games" and must keep the details of the promotional agreement confidential in order to qualify for payment. In other words, to get the money, video makers have to speak positively (or at least neutrally) about the Xbox One, and they can't say they're being paid to do so."