Maybe they should bring in the old Sunday league rule of one sub from each side reffing a half each. The penalty counts would even themselves up after half time...oh wait there...

The Video refs have already made use of a "virtual" line across the screen/pitch, this line being at right angle to the touch lines, for the purpose of determining off side at a kick.

Using the same "virtual" line by the video refs will certainly help to determine whether the ball has left the passers hands in a forward direction - if the ball crosses the line it is a forward and momentum would not be a concern. It is certainly worth using the system where a try is scored following a possible forward pass.

For that to work the virtual line couldn't be a static one like that used for offside. It would need to be a moving one. One moving in the same direction and speed as the ball was immediately prior to the ball leaving the hands of the passer.

But the pitch is a 2d area.

When looking at passes, any change in altitude resulting from the pass can cause confusion.

The best ref is the one that is reffing someone else's match.