Legal moving screen

[Sharpshooternes]

Can someone explain or post a video of a legal moving screen mentioned in C below? Thanks.

ART. 2

To establish a legal screening position:

a. The screener may face any direction.

b. Time and distance are relevant.

c. The screener must be stationary, except when both are moving in the same path and the same direction.

d. The screener must stay within his/her vertical plane with a stance approximately shoulder width apart.