I have been using this tool for over a year now, and its an excellent way to save videos.
http://bitbucket.org/rg3/youtube-dl/wiki/Home
You can specify to download the HD version, Mobile version, you can make a text file with 1 url per line and it will get all the videos in the file, you can also download all videos in a play list.
In the latest version you can use download templates for ways of naming your downloads
example which downloads the HD version of a video:
Code:
[chris@jumbo ~]$ youtube-dl -d https://youtube.com/watch?v=XxQH3MyphjQ
[youtube] Setting language
[youtube] XxQH3MyphjQ: Downloading video info webpage
[youtube] XxQH3MyphjQ: Extracting video information
[download] Destination: XxQH3MyphjQ.mp4
[download] 100.0% of 4.80M at 1.04M/s ETA 00:00
[chris@jumbo ~]$
You can also set it to quiet mode, so It doesnt output all that.