All dumb strange game channels upload the trailers of all other games without giving any credit. This isn't anything special.
He has almost 18,000 subscribers, I think it is more publicity. He isn't claiming that the trailer is his even.
i dont see it as a problem, it might give us more publicity!
I do understand both arguments here and see both a good and a bad side to people re-uploading trailers on their own channels:
The Good - It does most often give the game more publicity and more attention, and in some ways it can work as advertising.
The Bad - Many channels (actually from what I know almost all large channels or networks) will monetize the video by placing ads on it and using someone else's content to gain money for their network or organization, or just one person. In many ways this can very much be copyright infringement as the person or the network / organization is taking other people's content and putting it up to gain money, or even just publicity for their own channel or network or organization. It is very rude (even if it is not illegal) to take someone else's work (in this case Eksi's) and put it up as your own (or even just post it or put your logo on it) for views / publicity (good or bad) / even money.
Here's an example from when Terraria had its 1.1 update a couple years back (this is one example that I personally remember from when the trailer was released):
To promote their new update for their game Terraria,
the channel demilogic made a video / trailer showcasing the new content in their game. Then,
IGN posted the exact same video for their own channel (considering they are IGN, which is a huge network, they probably had permission to do this).
All in all, I have mixed feelings on re-uploading trailers and I can understand the different points people are making. I just wanted to share some information that could help us better understand what is going on.