I saw a programme ages ago which went through the strict policies surrounding things like advertisement, product placement and plugging that companies have to abide by but it seems YouTube is a grey area. The show explained that if someone was knowingly advertising a product and being paid for it; they would have to demonstrate that this was the case and not all of their opinions expressed were that of themselves or the product in question.
I tend to avoid many corporate mainstream gaming sites these days as you can never be sure if what is said is an opinion generated by the writer or just been placed in at a cost by the publisher. Many avoid the subject of negatives of a title and too much emphasis is put post-release on the reliance of get out of jail patches and updates. In the old days, if a game was not living up to expectation; magazines would happily lambaste the title as they had no fear of repercussions and opted to side with the gamer rather than keeping the publisher sweet due to £/$.
I tend to only watch independent YouTubers who aren't tied to a particular game or franchise. At least you'll get an honest and open opinion from them and not a 'I'm soo excited for this' scrpit from puppets like Ali-A or TmarTn. I think many people are unaware of the relationship with certain uploaders publishers have in terms of their content arrangement. Someone like the Cynicalbrit or FrankieonPCin1080HD are always on the side of the gamer and deliver a balanced and organised opinion and that's what I like to see from true gamers. I don't like this culture we see too often today where videos are favorable and unbalanced. Transparency is a key value which seems to be diminishing in the gaming arena today and at the end of the day; it's the loyal gamers that suffer.