The rugby referee's have it a bit easier, as a longer break in play isn't as annoying in Rugby as Football. They still aren't perfect remember. They are much better at communicating though, as they all act as professionals and not best mates having a giggle. Maybe that's because they are broadcast out.
VAR in football should be the guy in the truck watching it back at normal speed from all his angles (or with the ability to pause for offsides), and then telling the ref the correct decision.
No slow-mo, no rolling back 2 frames to show only part of a tackle. Watch the full incident at normal speed, in context and referee it as you would. The VAR is part of the referee team, this shite about the onfield ref needing the final opinion is a load of bollocks. The linesman doesn't ask him to come stand on the sideline and to explain an offside and let him make his own mind up.
This would take less time, be fairer in judgement and still pick up any obvious errors.