If that doesn't work I have another little trick.......
Open up the page that the video is embedded in using the Mozilla browser. It has to be Mozilla, not firefox or camino. On the bottom right corner of the window will be a little image of a lock. Click it. In the window that comes up, click the media tab. You'll see a pretty big list, mostly full of images. Somewhere in that list will be the video you're trying to get. In case you can't find it: To narrow it down, look down the "Type" column, a video usually says "Embed" in this column. Find your video, highlight it. Then click the Save As button at the bottom, and save it to your computer.
Usually works.