To other reviewers: this add-on has always required a companion app.
However, now they are forcing you to pay almost $30 for a license to convert the videos without a giant watermark on them. For me, this defeats the purpose of downloading videos. So, I will be uninstalling and finding an alternate. It would help if we knew more about who was maintaining this extension so we could have some sympathy for the developers. It was great while it lasted!