Jim Simon wrote:What does it do?
What should it do?
The master timeline (when enabled, and you have to do that at the start of the project) is a timeline with *all* of the clips that are in the project.
The syncing means that as you switch between your timeline and the master timeline you can see the same point in the same clip.
The usefulness of the master timeline is that you can do a remote grade on the camera and it will ripple through all your sequences.
I wanted to use it to apply fusion comps across whole camera angles - but there's no version of 'remote' fusion comps so it's a moot point.