Video Downloader Ultimate Pro supports Youtube (incl. playlists), Vimeo, Dailymotion, Yahoo, Facebook and many more. Since it's not a browser add-on it is extremely powerful and independent.
Detection and downloads work with Firefox, Chrome, Internet Explorer, Safari and Opera.
Convert downloaded videos to MP4 or MP3 to play them on your mobile device or on your MP3-Player.
Supports resolutions up to 4K (Ultra HD) on Youtube and other sites.
More detailed information around the features & functionalites of Video Downloader Ultimate
can be found at the vendor's website.