Actually the term "start codes" was used over and over by TiVo during the trial so don't blame me or E* for using it
E* just used TiVo's own argument.
I think the term "time stamps" are more appropriate. You said both the audio and video time stamps are needed to playback a TV program, that I agree, but the audio time stamps are not needed during the trickplays, only the video time stamps.
Because during a trickplay such as 4X fast forward, the DVR only needs to locate the video time stamps every 4x of the normal interval, while playing it at the 4x the speed, and at this moment of 4x play, there is no audio, only video is needed.
But you are right, once the user presses the play to return the 4xplay to the normal play, the audio and video will have to sync for the DVR to return to the normal play.