I don't have a carrier phone, and I like the startup video fine, I just want to get rid of the sound.

The proposed solutions won't work for me because (a) I will forget/don't want to be bothered fussing with the phone before or during startup, (b) my wife needs a solution that will "just work" - i.e., no startup sound.

If the sound file is part of the video I guess I could edit it to take out the sound and then put it back.