Video DownloadHelper - Browser extension to download videos from the Web
Keepv.id - Keepvid is the best online video downloader. Here you can download videos from 100s websites: Youtube, Facebook, Instagram, Twitter, etc.
Flash Video Downloader - Flash Video Downloader is a popular extension for Google Chrome browser for downloading wide range of files over the internet.
y2mate.tv - Y2Mate YouTube Converter is not just a video converter, but also an audio converter. You can easily convert YouTube videos to the format you want, such as MP4 (320p, 480p, 720, HD 1080p), 320kbps MP3, M4A, WEBM, etc.
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.
y2mate - Y2mate.