Windows 7 Tip: 
There are so many services which allows you to Download Online Videos, But xVideoServiceThief is the king in all of them. It has so many features which are very helpful. At it Supports 50+ Video Websites, Like Google, Youtube, Dailymotion and more.
See Also: 10 Easiest Way To download youtube videos
See Also: Top YouTube Tools
Here are the Cool Features of xVideoServiceThief:
· Drag & Drop functions: Drag and Drop the video link directly to the xVideoServiceThief
· Convert videos to most popular formats: AVI, MPEG1, MPEG2, WMV, MP4, 3GP, MP3 file formats
· Multilanguage: Use xVideoService in your language
· Session Manager: Save and Restore your download lists
· Download’s Log: Save a list with all downloaded vide (Date + Title + URL)
· Children protection: Disable adult website support
· Customizable websites: Select which websites are allowed and which websites must be blocked
· Tray Icon functions: xVideoServiceThief can work in background mode
Download xVideoServiceThief
Pretty good open source Video Downloader. But I use Free Download Manager for video files as it has a good built-in video converter and it even have a Bittorrent support!