A Pop-up launches when you visit certain websites. Their main aim is to try to catch the visitors attention and to bring something to their notice. As the plugin name suggests, it will help you pop-up videos on your site.
Currently the plugin supports only youtube videos. I hope to extent support for vimeo soon by the next version upgrade.
The pop-up is triggered when the user scrolls to the bottom of the page (footer). This makes sure user has least distractions on the site, only when he reaches to the end, he gets the pop-up. This makes its less annoying for visitors. However future version may provide customization over trigger.