Perhaps it’s a conflict in the version of the ffmpeg library used by pymedia, and the one used by Panda. You might need to compile a custom version of either or both of pymanda and Panda to ensure they both use the same version of ffmpeg (or compile a version of Panda that doesn’t use ffmpeg at all).
Or, save all the frames, and then quit and exit and run a separate process to join them, without having Panda loaded.
David