http vs https?

Hi, I'm getting the following error whenever I use playbackState='playing', though the video is playing: Failed to execute 'postMessage' on 'DOMWindow': The target origin provided ('https://www.youtube.com') does not match the recipient window's origin

This post on SO suggests it's an issue of http vs https in the api call. How can I configure the call to make sure it is using the correct url?