On its very first use, it used an image from a video that is not even in the post (but is in another post). When I went to the media library , a different image had been placed in the library, then what it had placed as the featured image.
Every time a post is updated, it places duplicate images in the media library, even if no changes have been made to the video in the post.
Between all of this, by the time I had used it on six posts, and updated those posts several times, my media library was quite bloated, and impossible to tell which images the plugin was currently using.
This was just a mess to deal with.
But still; thank you for taking the time to attempt to contribute to WordPress.