I am watching some video lectures on You Tube (licensed under Creative Commons - Don't know the version but I have right to copy).. So, after watching (streaming), how to download the buffered content..
I guess it would be on Browser Cache! but how to get it on HDD?
You can try youtube-dl - a python-script.
If you use a little script-magic, you can easily make it download a list of videos or all the videos in a channel.
EDIT: No need for script-magic. There are options allowing you to specify a file with video-URLs. And if given the URL of a playlist or a channel, it'll download all the videos there. Despite the name, youtube-dl works on numerous video-sites.
There are a plethora of Firefox and Chrome add-ons that you can use to download flv (Flash Video) from the web, including youtube. I would start there.
You can view the cache of Firefox (unfortunately only <22.0) with CacheViewer and look for large files.
