Can't modify volume of video opened through "Open File" function

For the project I’m working on, I need to be able to access an external library of video files and load them into the player. I do this through making a map of directories and feeding whichever one I need into an “Open File” function.This part works fine, however anything I try to do to the volume on the audio of these files doesn’t seem to work. What really boggles my mind is that the audio is playing even without a media sound component.

Sort of at a loss at this point. Any ideas would be helpful