The white board and screen you are talking about (around the 4 minute mark?) are used to light outside scenes. The white board is a reflector, which essentially means they are using the sun as natural light, and are controlling it by choosing which way angle it will hit the actors at.
Fwiw, the net's a "double" (with the red trim). A "single" has green trim. You'll see scrims used on lighting, with the same colours. It cuts down the light passing through it. Light control is extremely important on set; even outside.
Btw, you can get that handheld bounce board at Home Depot for a few bux, in the insulation aisle. Silver on one side; white on the other. Cut it in half, if you like, to make square "pizza boxes" - and improve them with by covering them in different materials for different purposes. Maybe some matte metallic silver instead of hi-relflect. Play around.
...and that's all I'm examining for you, from that flick. It was awful.
Fwiw, the net's a "double" (with the red trim). A "single" has green trim. You'll see scrims used on lighting, with the same colours. It cuts down the light passing through it. Light control is extremely important on set; even outside.