There are usually two rectangles over videos before the final video is released. I guess they might be there to help the camera operator.

• What purpose do they serve  ?
• Do they have a specific name  ?

Here is an example:

There are usually two rectangles over videos before the final video is released. I guess they might be there to help the camera operator.

• What purpose do they serve?
• Do they have a specific name?

Here is an example:

There are usually two rectangles over videos before the final video is released. I guess they might be there to help the camera operator.

• What purpose do they serve ?
• Do they have a specific name ?

Here's a link to an example :

There are usually two rectangles over videos before the final video is released. I guess they might be there to help the camera operator.

• What purpose do they serve ?
• Do they have a specific name ?

Here is an example: