I haven't seen this guy at all before this post showed up for me. I guess, yes he isn't crediting anyone, but also his video descriptions aren't really saying that he made the stuff(again from the like 4 i actually saw from the links above.). Yes he should give said credit where its due, but is he stealing stuff or just making resource pack/data pack showcases? Again, perhaps other vids of his do involve him offering alternate downloads for the original creators stuff, but I haven't seen this as of yet.
Still, how does anyone manage to get over a million subs off of 40 second vids lol.