I am in the same problem as you are, same camera. when I travel, I shut my computer down because if a power failure, the ups drains and shuts down the computer, then nothing happens. I have my site updating with Davis Weatherlink and thatway, all I have to do is keep my router/modem on the battery backup.
So I would like to be able to have the webcam work independently. It is plugged into the outlet, so if the power goes down then comes back on, it resets it self with themodem. Anyway, in the meantime, I would want to send images as you are.
With the foscam, i thought I could send the image via IP address to my ISP. but foscam sends not just one name, but as suggested webcam.jpg plus every date and second with that. It used to, way back, be able to send a single file that over wrote the previous file and no problems, but now I have this issue as you did.
Ihave tried every IP address and the camera simply won't attach the server with weather underground. Certainly I am assuming someone must have a similar camera that needs an ftp IP address to make this work.
Out of Curiosity, does anyone do it this way, upload directly from the camera and if so, what camera brand?