Downloading videos with Safari 7.0.1 on OS X mavericks
Option-command-A is just a shortcut for showing the resources tab of the web inspector. It still works, but you have to enable the develop menu first.


Check Preferences > Advanced > Show Develop menu in menu bar.
Open the resources tab of the web inspector.
Look for a resource for the video under the other folder. It's named videoplayback in YouTube. If it doesn't show up, try reloading the page.
Double-click the resource to open it.
Focus the location bar and press option-return to download the video. If you try to save the page, Safari only saves an empty file.


Note that some sites like twitch.tv use multiple resources for long videos.

Another option is to use youtube-dl. You can install it with brew install youtube-dl after installing Homebrew. Some examples:

youtube-dl https://www.youtube.com/watch?v=1234567

youtube-dl https://www.youtube.com/watch?v=1234567 --extract-audio

youtube-dl http://www.twitch.tv/b/1234567 -o ~/Downloads/'%(uploader)s %(title)s %(id)s.%(ext)s'

pbpaste|grep -o 'https://www.facebook.com/photo.php?v=[0-9]*'|parallel youtube-dl -o '%(id)s %(title)s.%(ext)s'

curl -s http://gdata.youtube.com/feeds/api/users/someusername/uploads|grep -o 'http://www.youtube.com/watch?v=[^&amp;]*'|sort -u|parallel youtube-dl