I've attached a picture of the toolbar button that should appear when you install KeepVid.
I appreciate your help.

Are you doing this in Safari or Firefox? On the KeepVid site there is a "KeepVidBookmarklet" that says drag to my toolbar. In Safari, I dragged it up to where my URLs are and it says "Keep It" but there is no V. However that 'Keep' it seems to work for identifying a video for download on You Tube. It does not work on another site I frequent.
I have the CTF extension installed and just right click on a YT video, or any other video that gets offered in Flash and MPEG-4 format, therefore it will not work with every site, I can choose "Download Video", but maybe you have to check the Extension settings for CTF first and enable the "Download Video" menu item in "Contextual Menu Items".
Can you provide a link to the page you want to download from? Have you tried Firefox and the Video Download Helper add-on?
I'll play some more with it and then get back with you on this. I'd like to get this into the Guide below. Thanks for the help!
I've looked through MR Guides and don't see one on this subject so I am preparing a Guide to publish. This is what I have so far. For anyone, please let me know what needs to be edited or added. Thanks!
To Be Published as a MacRumors Guide:
Downloading Video
Multiple solutions for downloading video from You Tube and other sites. For myself, this is so much better than streaming the video which can be jerky and slow. Thank you
MaxOSX Hints for getting me going!

As a Mac user, due to Apple moving away from Flash I've decided there is more utility using MP4.
Summary First
1.
KeepVid- A site which allows you to download video. For simplicity working with You Tube, this site is a winner, but it may not see video on other sites.
2. If you are dealing with You Tube
and other sites, the Safari method is the winner because the Activity Window, allows you to snag videos on other sites that KeepVid may not be able to see. It provides simple file download in FLV (flash) formats and then convert them into MP4 using Handbrake.
Helper Programs and Web Sites
*
KeepVid- Site which allows you to download video. Works well for You Tube, but on 3rd party sites it may not see the video.
*
Handbrake does a an outstanding job of converting FLV to MP4.
Intel Handbrake.
PPC Handbrake.
*
QTAmateur, universal binary, runs in 10.3.9 to at least 10.5.8 and will convert FLV to MP4, however it reduces the size of some higher quality videos. When I start with a 6.6MB FLV file and convert it to MP4. I end up with a 2.6MB file with a noticeably smaller display. Under settings, I don't see a way to preserve the larger format.
*
Fastest Free You Tube Downloader. You Tube only?
*
Click To Flash Safari extension that I've found hard to figure out.
Safari
1. Find the Video url with Safari.
2. Select Command/Option/A- which opens the Activity Window.
3. Start the video. (For the applicable file to appear in the next step. You'll see the video progress bar.)
4. In the Activity Window there will be a long list of files. When you start the video, you should see a new large file load in this window. While many of the files will be in the KB range. The video most likely is 1+MB and can easily be 50MB or more. That's the video file. It maybe located near the top of the list under sub categories that say something like 2 items, 8 items. It may download as a .FLV (Flash) file or labeled as a "videoplayback" file. After it is done downloading give it a better name if you desire.
5. If you intend to play this file as Flash, and it does not have the .flv suffix, add that. Then install
Perian on your Mac. Perian adds video formats that QT can use, among them .flv (flash) files. Do a "Get Info" (Command I) on the file and tell it to open with Quick Time. Are you happy with FLV (Flash) you are done.
6. If you prefer MP4 skip step 5 and use Handbrake to convert these files to MP4 using the appropriate version:
Intel Handbrake.
PPC Handbrake. Enjoy!
Firefox
1. In Firefox, download
Video Download Helper and install it. Three little balls show up in you menu.
* Use it to download .flv files from You Tube.
* Use to download .mp4 files from You Tube.
* Some sites clearly have video, but Download Helper may not recognize the video. Then use Safari as described above.
* When I try to download a file and tell Download Helper to convert it, I've been getting an error message that conversion can't take place. It may have to do with this note on the Video Downloader site:
For Linux and Mac, we do not have a specific FFMPEG distribution to connect to DownloadHelper. Instead, the conversion relies on the distribution that has been installed separately on the computer. Of course, this can lead to conversion failures as the version of FFMPEG may not have been compiled with the features required by the chosen conversion parameters.
I'm not sure what FFMPEG conversion program they are referring to?