If we knew the sound bug could be fixed! (Relic believe the sound bug occurs when the screen is being scrolled rapidly and anecdotal evidence from players supports this. When trying to fix the bug they added camera tracking to replays to try and establish if this link was correct.However the sound bug refused to play ball and show up in replays with the same camera movements as the live games in which it occured so back to the drawing board...)
Unfortunately all camera actions are still client-side. The camera entity is not networked and it's values are not CRC'd in any way. There is also no camera data in replays.
The "Follow player" feature is implemented by centring the camera on the last action a player performed. For example, if the player gives a move command to a squad, the camera centres on the destination of the move command.
Note that squad selection (what units the player has currently selected) is also not networked or stored in replays, thus the "Follow player" feature does not move the spectator camera as the player selects and deselects units.