The great thing about using this plugin is that once you've set it up, you'll never have to do anything in your website to add new videos. All you need to do is upload them to YouTube and add them to the playlist you've linked to, and they'll automatically be added to your site.
If you want to add extra content to the posts holding your videos, you can do so. Just edit the posts in the normal way, adding text, images, and anything you want. These will be displayed as well as the videos.
If you want to create new playlists in future, you just do this in YouTube and then create a new category on your site and add the playlist in the settings for the plugin, assigning the new channel to the relevant category.
You can ...