The three built-in layouts provided by default:
grid: Equal-sized tiles in a responsive gridspeaker: Dominant speaker large, others in filmstripsidebar: Main speaker large, others in vertical sidebaroverlay: Main speaker fills the area; others float on the right edge as an overlayscreenshare: Active screen-share fills the main area; others sit in a filmstrip below
Built-in layout mode identifiers for the video grid.