You are trying to download a video from your Sony Handicam DCR-TRV280. You have a picture package that came with that camera installed but you can't get it to recognize that camera.
You would want to install your software first before hooking up your camera to your computer.
Basically, you install your software that came on CD-ROM and possibly DirectX if it asks to install that too. You would then reboot your computer after software installation completes and is successful. Once your computer reboots into Windows then you would hook up your camcorder to your computer via it's USB cable.
Then try to run ImageMixer and see if it will detect your camcorder. You may need to remove your camcorder software and then reinstall it before hooking up your camera properly to get it to work. You can view a DCR-TRV280 manual on Sony's support web site if you don't have one, that has installation instructions with pictures.
You can skip to page 74 of that manual for instructions. Click on "Camera Operations Guide" link to view a pdf manual. Try removing ImageMixer from your computer, reinstalling it, then hooking up your camcorder. It might be necessary to start from scratch.
If ImageMixer prompted you to install Flash Player, test to make sure it installed correctly. Make sure you are logged into your Windows 2000 computer with administrator rights or your administrator account. Also, you can try moving your Camcorder to a different USB port on your computer with ImageMixer software installed.
Even if you don't start from scratch by reinstalling your software, Windows should detect your Camcorder again and should see it as a different device on a different port, which may fix your issue.