This thing kept trying to install unauthorized software and being flagged by my antivirus. When disabled of its privileges, it asks to install a "companion app" or won't do anything. Beware of add-ons that only run in any kind of elevated mode. Uninstalled.
Video DownloadHelper is by far the easiest to use method to save videos for future viewing. Right-click in context menu and select download, and your video is quickly saved and automatically named. Highly recommended!