good points, and i've sent a message to vsc. it will be interesting to hear if she was aware of this. she might have uploaded to their site for all we know at the moment.
and yes, she's got quite upset in the past, with some of the yt channels who were doing this, as they were ignoring her requests to remove her content. if i remember correctly she even threatened one of them with a dmca. but then they were running ads on the stolen content. i think at least one of them eventually got shut down by yt, since it was against the tos.
am i correct in thinking that blenderhub aren't hosting the videos themselves, and instead embedding the yt player with links to the original content? if that is the case, it's still still not ethical (if they don't have permission) but it's not as bad as re-uploading.
regarding communities, like yourself, vsc answers a lot of questions from her viewers. especially as her videos are usually intended for beginners, and if users are watching her videos on some other channel, she won't get the feedback or be able to assist them if need be.