It was marked resolved since there was no activity on it for 8 months.
Anything regarding the frontend display of things is going to be dependent on the active theme you have going, to be honest. Changes around the topic are going to need to be done at the theme level.
The plugin here doesn’t touch the template or frontend CSS at all. At the heart of it, the plugin handles detecting if there’s a video, and if so, using the Youtube/Vimeo APIs to fetch screenshots provided by those sites. When a video is found, the plugin uploads the image to the media library and assigns it as the featured image of the post in question. At that point, the plugin’s job is done.
Hope that makes sense, but let me know if you have further questions.