I'm not familiar with either of them, only heard of Syndicate while watching Nanners' vids and haven't seen them play together in years. But if it's true that they were saying the videos were sponsored by said company, they're technically in the clear unless YouTube has other terms or the US has other laws that state they need to say the company is owned by them as well.
The way I see it (from what I've read); they've created videos showing people how they can use said site and win stuff, without disclosing that they own the site, so they actually took advantage of their fan base. I know some companies have done similar to this, primarily parent companies who have multiple subsidiaries, who might do an ad where they put down another product to make "their's" look better when it's really the same company. I don't think it's blown out of propportion, they gamed their fans and should pay for it.