I'm afraid I don't remember the name of this episode, but it's towards the end of the series, because Ed's got a pretty long hair there.

Anyway, in this episode Ed and Joel are having a conversation and when the camera is on Ed's face, his braid is on his shoulder (on the front) and when the camera focuses on Joel's face, Ed's braid is on his back. This goes on for about 3 or 4 times.