part of the problem regarding video refs decisions is that they only get the video feed not any sound, the whistle might have been blown before long made the final effort and grounded the ball but the video ref wont know that

Although initially it was clear Cockayne had held the ball up I thought there was enough reason to suppose Long got some part of the ball down as he legitimately struggled to do so.

He couldn't see whether the ball had been grounded but it was reasonable to suppose that it had. It was therefore a correct call and precisely why Benefit Of The Doubt should be available to the video referee.

What purpose would be served by handing such decisions back to the on-field referee?

You said he couldn't see if he got the ball down. This is the point. You said supposed I would say he guessed and that's wrong.

Agreed, that's exactly what I said and that's why it is awarded as Benefit Of The Doubt.

There will always be occasions when the ball is obscured under bodies, where the referee, the in goal judge or the video referee will have to make an educated guess.

Just because no-one can see the ball touch the ground doesn't mean that it hasn't.

How many times do we watch seemingly endless repeats of the same thing when the vidio ref is "in action"? If he has to look at it more than once there is "doubt" or why the replay
As benefit of the doubt has to go to the attacking team surely any try that needs looking at more than once is a try.
Thus, a stupid rule