If a web camera has both IPv4 and IPv6 addresses, motion tries to connect to 0.0.0.0:80. Entering only the IPv4 address to /etc/hosts solves the problem.
Hello, I recently took over maintenance for the package motion in Debian. This bug is quite old and related to old version of motion. Since it hasn't got any update since 2012, I have the sensation it can be closed. I'll wait a little bit for a feedback before closing it. /Nicolas