Cannot disable download

This is not a bug. The settings of the H5P plugin will only prevent users from downloading the whole H5P content itself. It does not “protect” any media inside the content from being downloaded via the browser directly.

“WP Content Copy Protection” can’t act here, because most H5P contents live inside an iframe which “WP Content Copy Protection” can’t access. You’d have to set up your own solution that can inject similar JavaScript to H5P contents.

However, ultimately you cannot prevent getting access of the media even if you block using the right mouse button. People can get hold of the media easily using the browser’s development tools anyway. If they can see the media, they have it already.

All you can do is to make it harder for people with only rudimentary knowledge of the web and worsen their experience at the same time, because access to their regular browser features via the right mouse button may be impacted. You will not stop those who really want to get hold of your media though.

Please see e.g. https://www.sitepoint.com/dont-disable-right-click/ for more detailed information.