This is on youtube, there's nothing we can say against him as moderators anyway.
Also, he makes some blueprints available, but he never said he made them, so we wouldn't consider this a steal. By our rules it's true that he should have credited the authors, or at least precised explicitely that he didn't make them (we allow this option when the author is unknown), but redistributing a rocket is allowed. Even on this forum some people post rockets they found on youtube, it's fine as long as they credit the youtuber.