It's difficult to show color flags well during an online meeting. The following video shows two ways to show color flags more effectively.
1–using a webcam management software (like ManyCam or SplitCam) and without a green screen
2–using green screen and Zoom's virtual background function (many of the webcam software has similar function)
–Timers can add a bell along with the changing of the color flags
–Speakers can pin the Timers' screen (when using Zoom or Ring Central)
–Adding the words “Green/Yellow/Red” to the signs will help, even when colors are not shown properly