When are you getting the errors? Is it when you enter the URL into AbelCam and use the Test button? Or does the Test work but then it fails when you try to actually start the cam?

If Test works but it fails when you start the cam, try using a lower framerate (like 1 FPS) just to see what happens. I have no idea how quickly this cam's snapshot.cgi routine can handle back to back image requests.

If it doesn't even work when you Test, that's almost always the sign of the URL being entered incorrectly. Are you positive you got the URL right? Missing a port number maybe?

Also, on the form where you enter the URL you have the option of using Sync or Async operation. Try both.

And lastly, I'm only guessing (because of the name "snapshot.cgi") that the cam outputs individual jpeg images rather than a mjpeg stream. Obviously you have to make the correct choice of jpeg or mjpeg when you configure the cam in AbelCam. What are you seeing in Firefox? A single still frame (jpeg) or a moving, possibly flickering, stream of images (mjpeg)?