While the substitute and advantage rules were confirmed for 2012 on Tuesday, use of video technology will be discussed at a meeting in November.
McLachlan said he was a fan of the idea but admitted it would be complex to implement an effective system, with the League debating the benefits of having an official in the grandstand with access to broadcast replays.
"He can talk to the umpires in real time, so he will see the first replay and if there's something to look at he can tell them to stop and not make a decision or give them very quick feedback," McLachlan told afl.com.au's Trade Week Radio.
"The trouble with that is there may be a ball that hits the post that is not captured in the produced vision that people see. But then the producer might find something after the play has moved on, which has the potential to embarrass you further if you've got a decision declared legal in the first pass, but then a camera angle finds it a wrong decision."
The debate re-surfaced when Collingwood's Sharrod Wellingham was awarded a goal in the Grand Final despite it clearly glancing off the post.
McLachlan said it was vital the situation never arose again.
"It (technology) has to be implemented," he said.
"If Geelong lost the Grand Final by less than a kick there'd be serious and legitimate outrage from Geelong supporters when everyone knew within seconds it had hit the post.
"I do believe we have to use technology. It's a question of how you do it without potentially creating more problems. Sometimes you're not able to pick it up and we don't want to delay the game.
"My personal view is you should be using technology as long as it doesn't slow down the game."
