The reason, according to GNUCITIZEN, is because of an Adobe Flash issue in the wild. UPnP, or Universal Plug and Play, is a protocol that allows devices on a network to find each other, as well as to allow network clients (e.g. instant messengers, file sharing programs, etc.) to open ports on the router. The latter application for UPnP is the problem, in that a malicious piece of code can completely open the firewall of a router and negate any security that was in place.
If you have a home network in place and your video machine is hooked to it, go ahead and disconnect that machine from the network and give yourself a network security audit. First, go into your router settings and make sure UPnP is turned off to avoid any problems down the road. Then, make sure your router’s password is something other than “admin”, “password”, “1234”, etc. If all of your hardware supports it, use WPA-PSK (or even better, WPA2-PSK) for your wireless network. Also, don’t forget to check for firmware updates from the manufacturer of your router–but don’t forget that most routers require updates to be installed from Ethernet-attached computers (not over Wi-Fi).