“Looks like Madison was ready to have an environmental film festival,” declares Gregg Mitman to an overflowing crowd at the Orpheum Theatre on Friday night. The entire lower level of the auditorium is filled for the kickoff of Tales from Planet Earth, a free showcase of nearly two dozen movies that tell stories about the environment and how humanity interacts with and depicts our shared world. In fact, hundreds of people stand outside in a line running down State Street, waiting for a chance to get in for a talk by writer Bill McKibben and a screening of Everything’s Cool, a documentary about the political battle over global warming.