I need to add a new functionality to a wordpress plugin, (Presto Player, video player)

I need to add a new functionality to a wordpress plugin, (Presto Player, video player) the new function would be to add a button on the lower right side, that says "next chapter" and appears in the last 5 seconds of the chapter that is in playback, something similar to what netflix and other players like amazon prime video have, the idea is that the title of the button and the time where it will appear can be editable, I have the plugin in pro version.