Much like standard media players, cineSync has buttons to control the playback of movies - Play/Pause, Step Forward, Step Backward. Skip to Beginning and Skip to End are available only in Classic View.

You can also use the space bar to play/pause playback, and the keys J, K and L can be used to play the clip backwards, stop, or play forwards. A full list of available keyboard shortcuts can be found here.
You can also jump (or 'scrub') to a frame by clicking anywhere on the timeline - cineSync will jump immediately to that position and everyone in the review will be placed at the same position.