Video download from video site such as youtube.com has many methods, there are allready many software downloader , online url conversion utility to do the job, however, using userscript is a better way is you have already installed browser-addons.There are basically two browser addons are recommended here, GreaseMonkey for FireFox and IE7Pro for Internet Explorer. Each of them has correspondent user script site, http://userscripts.org/ for GreaseMonkey and http://iescripts.org/ for IE7Pro.
1. General Video Download Scripts Video Link Grabber
This script puts a link at the bottom of the page with the location of the stand-alone video-player of a lot of sites (see tags). Can be used to copy/paste into forums... You can also click on the link to view the video fullscreen.
FireFox: http://userscripts.org/scripts/show/9147
Internet Explorer: http://iescripts.org/view-scripts-78p1.htm
Video Downloader
A video download utility powered by videodownloader.net http://javimoya.com/blog/youtube_en.php . Video Downloader allows you to download videos (to your computer) directly (and easily -just one click-) from most video sites. You can download from: Angry Alien, Blennus, Blip.tv, Break.com, Dailymotion, Double Agent, eVideoShare, Free Video Blog, Google Video, Grinvi, iFilm, Keiichi Anime Forever, Metacafe, MySpace, MySpace Video Code, Putfile, Totally Crap, vidiLife, vSocial, AnimeEpisodes.Net, Badjojo, Blastro, Bofunk, Bolt, Castpost, CollegeHumor, Current TV, Dachix, Danerd, DailySixer.com, DevilDucky, Double Agent, EVTV1, FindVideos, Hiphopdeal, Kontraband, Lulu TV, Midis.biz, Music.com, MusicVideoCodes.info, Newgrounds, NothingToxic, PcPlanets, Pixparty, PlsThx, Revver, Sharkle, SmitHappens, StreetFire, That Video Site, VideoCodes4U, VideoCodesWorld, VideoCodeZone, Vimeo, Yikers YouTube and ZippyVideos.
Internet Explorer: http://iescripts.org/view-scripts-52p1.htm
Video Download
Save video clips from YouTube, Google Video, Myspace, Metacafe, Break.com, Putfile, Dailymotion and Sevenload. The script shows a small notice-bar at the top of supported video-pages. Upon clicking the notice-bar download links are shown on a small results page. Right-click to save the files. Results page and images are part of the script and not loaded remotely.
FireFox: http://userscripts.org/scripts/source/8427
FireFox: http://userscripts.org/scripts/show/4037
Internet Explorer: IE7Pro user scripts(default installed).
2. Special Video Site Download Scripts Youtube Video Download
FireFox: http://userscripts.org/scripts/show/8177
FireFox: http://userscripts.org/scripts/show/7880
FireFox: http://userscripts.org/scripts/show/3982
Internet Explorer: http://iescripts.org/view-scripts-3p1.htm
Google Video Download
FireFox: http://userscripts.org/scripts/show/5821
Metacafe Video Download
FireFox: http://userscripts.org/scripts/show/4316
LiveLeak Video Download
FireFox: http://userscripts.org/scripts/show/6442
Internet Explorer: http://iescripts.org/view-scripts-71p1.htm
6Rooms Video Download
Internet Explorer: http://iescripts.org/view-scripts-72p1.htm
Tudou Video Download
Internet Explorer: http://iescripts.org/view-scripts-73p1.htm
3. Sex Video Download Scripts RedTube Video Download
FireFox: http://userscripts.org/scripts/show/8691
Internet Explorer: http://iescripts.org/view-scripts-61p1.htm XTube/Pornotube Video Download
FireFox: http://userscripts.org/scripts/show/5208
Internet Explorer: http://iescripts.org/view-scripts-62p1.htm