I haven't looked to see if there are restrictions in terms of what can and can't be shown about Steam. They may have "non disclosure agreement" rules that you sign in order to put the game on there that would prevent streaming tutorials about it. So I'm not sure at the moment, we'll find out (much) later since this is something you only care about once you need to ship the game :)
Yeah, the Steam API is guarded under NDA.
But maybe they could make an exception given the educational aspect of HMH, so that the live streams could be password protected and viewers could sign an NDA to watch it! :D