Chopper - moi? - quelle horreur!
The serious answer is - it depends...
If I think it went forward - ie travelled discernably forwards ie towards the opposition DBL, then I would blow up.
That might vary if it was apparent to me that the ball was thrown behind the passer and only went forward due to momentum and distance travelled.
That might also vary on my line of travel, I might see it as flat or backwards because I am travelling at considerable pace (perhaps in the old days, anyway) in line with it.
But in the end I would make an instant judgement, based on a multitude of small clues. I don't want to get to too prescriptive position that simply confuses everybody.
99% of the time 99% of players and spectators and refs recocognise what is and isn't forward. And on the odd occasion where there is a difference of opinion we have all the fun of analysing it in repeat slow motion from multiple angles - not a luxury I ever enjoyed on the pitch.
So my view is actually - it's forward if I say it's forward, and if you disagree that's your privilege - but we will still have a scrum here, their put-in - so tough titty.