Video DownloadHelper - Browser extension to download videos from the Web
HTTrack - HTTrack is a free (GPL, libre/free software) and easy-to-use offline browser utility.
FastestTube - Youtube fastesttube downloader will make your internet expirience faster harder beter stronger.How to merge video and audio .
WebCopy - Cyotek WebCopy is a free tool for copying full or partial websites locally onto your harddisk for offline viewing.
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.
SiteSucker - SiteSucker is a Macintosh application that automatically downloads Web sites from the Internet.