How to prevent a function execution with another function?

I am trying to integrate a LMS plugin with a membership plugin.

My goal is to allow all visitors to see courses and even lessons pages, but the corespondant videos would be restricted to members (of course).

Well, I found the LMS Plugin function responsible for displaying the video-HTML portion.

Is there a way to write another function to prevent that function to execute if the user is not a member (I already have the if statement for this ready).

Hiding div video element with CSS would not be a reasonable solution, of course.

And I can’t hack the LMS Plugin code, because it would be difficult to update later. I need to this using my own plugin, or inserting code on the functions.php file.

Thus my question: How to prevent a function execution with another function? Or is there any other way to do this?