(necessitates that we show or at least know ahead of time the outline of the camera frame if the aspect ration of the MC window differs from the aspect ration of the output video)

A few ideas on this...

Basic screen-flow:

• enable/disable via a new button in the replay viewer menu (bottom left corner)
• on enable, a pop-up appears to enter the setting
• submitting hides the pop-up & menu and shows the overlay

Functionality:

• enable/disable button
  • enable shows the pop-up
  • disable hides the overlay
  • button icon is the 3x3 grid
• setting pop-up
  • three rows:
    • intended resolution (e.g. 1920 x 1080)
    • intended ratio (e.g. 16:9)
    • submit & cancel buttons
  • editing one of resolution or ratio updates the other
    (maybe hint to nearest common resolution - via simplifying ratio fractions and/or lookup table)
  • submitted resolution will be pre-set in render settings for that recording
  • cancelling will hide the pop-up, but keep the menu
• overlay
  • greys out screen regions, that will be hidden in the video
  • equally splits the resulting screen space with the 3x3 grid