Solution is quite simple and here is it quick for you: Open a page with flash. Wait till it’s completely downloaded, then fetch if from /tmp/.

A longer explanation would be to a youtube page and load the entire movie like so:

When you see the movie has loaded fully, without interruptions from the user (you). You can find it in /tmp/:

Now you just copy it to where ever you’ll like. If you want to convert it, you can open it with avidemux or Kino and then export it to .mpeg or whatever format you’d want.

Using ffmpeg:
ffmpeg -i "/tmp/Flash8CRIFL" "mechanical hand.mpeg"