Brian, just to make sure I didn’t mis-communicate. Lectora uses a built-in version of the actual mediaElement.js player. I believe the built-in version only has a limited amount of the capabilities of the full mediaELement.js library (I have never delved too deep into the built-in versions API because it’s split into multiple minimized libraries and what I have customized was more of a fight than just adding my own) but for most simple applications it works perfectly.
If this is something that interests you and you want to pursue it further feel free to reach out. I will try to help as best I can, time permitting.