Seen a similar letter to that before posted. I'd remove the particular file they are concerned with. Otherwise you not only risk your account with Cox but possible MIAA court action. The MIAA are particularly concerned about those CAM type videos that are about just released or not yet officially released videos.

Perhaps best to keep a low profile with sharing for a couple of months or so. Changing ISP is an option. New ip address, & besides, Cox is known to block or shape some p2p use for some users.