SSL for private slides
Many online collaboration platforms already secure content over SSL, and many browsers simply block embeds from non-SSL sources on SSL pages.
Embedding decks in the upgraded edition should be over SSL, or whatever protocol the main page is in. This is why the YouTube embed code doesn't give "http://' in the source attribute, it just gives "//" so the videos can be embedded on SSL pages.
The share panel now generates protocol relative embed paths, so embedding a deck under a secure domain will automatically use the SSL route to the deck.
Any chance you could host it over https too?
JP Etcheber commented