Ok Tom I understand now.
If you can see the video cam from your internal network, it's cause your on the same network as the UDP stream.
Your firewall is providing NAT not port forwarding!.
What is NAT:
You lookup a website on your PC, it connects to the Linux gateway which then in turns changes the TCP packet headers to match its own IP info and forwards on to it's next hop, then the response packets come back to the senders header info, the gateway then matches this to it's packet table and gives it to the internal pc that first sent it.
Now if someone just wants to look at your video stream data, they connect to your firewall which in turn says no your not an internal system in my NAT table that sent the packet in the first place and the packet are dropped.
Your Windows 3com Cam is working in the following way from looking at that netstat -a info.
192.168.0.3 streams the data over UDP on port 1177
192.168.0.3 has a port ready for a connection to start the stream on tcp port 1177
Other systems connect to the 192.168.0.3's tcp port 1177 from there windows netbios port.
So what you need to do if you want others to see your video stream is to port forward through your firewall.
The way you would do this is with some free software called "ipmasqadm" this needs to be downloaded and installed on your system.
Then it needs to be linked to the MASQ mod in your system with the command: #modprobe ip_masq_portfw
Then you need to forward over the correct information to your internal system from you external IP address.
With the following lines:
(your_external_ip is whatever your linux's ISP's ip address is to your DSL router)
ipmasqadm portfw -a -P tcp -L your_external_ip 1177 -R 192.168.0.3 1177
ipmasqadm portfw -a -P udp -L your_external_ip 1177 -R 192.168.0.3 1177
Or something like this,