If the complaint includes the player using cheats, and you're not 100% sure the evidence you provide will be enough, PM the video to an admin so we can keep an eye on him and confirm it without him even knowing about it.
If the complaint is not cheat related, there's no point in making it a secret..post all the evidence you have and you'll get a response. Him saying a few words doesn't mean anything because we focus on the evidence. If the evidence doesn't prove he is 100% guilty your complaint will get rejected, regardless of him making somekind of comment or not.