Adding the Highest Zindex to a Plugin

I have a plugin that I am using and cant seem to get a response from the author. The plug-in basically places “walk on videos” on my word press site. Currently I cant see the videos but I can hear them. So I’m assuming the Z index isnt set high enough. There doesnt seem to be any CSS in the plugin file… Is there a way I can set the plugin to have the highest Z index? Thanks!