The application called... YoutubeFisher is very easy to use and portable. Moreover, you can download any number of video or audio simultaneously.
To download a video or audio, run YoutubeFisher , then find a video from YouTube. Copy the URL in the address bar then paste it in the app. Now select Download video or Extract Audio button to download video or only audio.
Moreover, if you want to download another video, just click Download More button and proceed as given above. After finishing the download, it will ask you the location to save the downloaded video and/or video. It’s that simple. Enjoy
The application is clean and it only retrieves the video and saves it in the format chooses by user: full-HD, HD, HQ mp4, flv, mobile 3gp or audio mp3.