DDLVid - Online Video Downloader - Download from various popular video and music websites. Save into MP4 and MP3 formats.
Video DownloadHelper - Browser extension to download videos from the Web
Twitter Video Downloader - Download Twitter Videos - Online, free twitter video downloader.
FlashGot - FlashGot is a browser extension for Mozilla Firefox that is designed to make it easy to download a whole batch of files in one go. The extension is open source and free to use, but it is no longer compatible with the most recent version of Firefox.
TubeOffline - . Fast & Easy to use! 2.
ClipGrab - A friendly downloader for YouTube and other sites