There is the Free iTube Grabber which can capture almost any audio and/or video stream (it says here) but only works with Intel Macs.
http://itube-grabber.en.softonic.com/mac
Firefox Download Helper is also supposed to work, you have to be logged into YouTube first.
and the RealPlayer Downloader that comes with RealPlayer SP for Mac from:
http://www.real.com/realplayer/mac
which also downloads videos from YouTube.
There is also iTubeX which allows you to download videos (Flash, HTML5 and others), .mp3 and .swf files from almost every website as easily as possible:
http://www.macupdate.com/info.php/id/27604/itubex
Lastly: How to download Flash videos and play them in Quicktime using Perian is explained here:
http://perian.org/#watch
It's the video at the bottom of the page.
Last but not least (as some of the above may not work with Snow Leopard or Lion) there is the 'pwn trick':
For example, the full youtube site for your movie is:
http://www.youtube.com/watch?v=bC2XIGMI ... e=youtu.be
As soon as the movie starts, pause it and add 'pwn' in front of the youtube part of the url so it looks like this:
http://www.pwnyoutube.com/watch?v=bC2XI ... e=youtu.be
Hit Return and then follow the instructions.