In the factory setting, we enable the "Black-bar detection" so that the sync box would automatically exclude the letterboxing (i.e. black bars) along the edges of the video from syncing. This means, when you're watching a widescreen video and the top side of the screen is black, the sync box will detect further inner part of the screen and make lights sync to the that area.
If you do not want the letterboxing, or the black bars excluded from syncing, you can scroll down in the video sync page and tap on the toggle to disable the Black-bar detection.
Black-bar detection disabled:
