Hi
Old thread I know, but just to advise that I am having issues with this too.
Trying to embed H5P from a Wordpress site in to 3.0.4 - just won't work, even if I switch Trusted Content and Object/Embed on.
However, embedding in to 3.3.x DOES work. Very weird.
So maybe something was fixed in 3.1 onwards, as everyone seems to be reporting this is OK.
Dan