The romantic scene is believed to have taken place before he jetted off to Papua New Guinea to hike the Kokoda trail, in the Kimberley region of the Norther Territory.
Nick can be seen strumming a catchy tune as a man bent down on one knee to propose to his girlfriend.
The video was shared by Kimberley Spirit Safari Guide Scotty Connell.
It has been an emotional ride for this year's Bachelor, Nick 'Honey Badger' Cummins, who has seen a slew of single ladies battle it out for his heart.
Viewers thought front-runner Brittany had won Nick's heart after he sent Sophie home.
'It's been a hell of a ride Sophie,' Nick started. 'Every time I'm with you I have a good time.'
'I like you a lot Sophie,' he added. 'And when I say those three words - I Love You - I want to say it with my whole heart.
'And when we're both happy, with true happiness. I am not able, with all my conscious, to whole heartedly commit to you.'
But those who thought Nick and Britt were about to live their happy ever after were in for a rude awakening when he came out with a bombshell revelation.
'I can’t give 100 per cent of me to you,' Nick told Brittany. 'My head is very cloudy. Right now I’m a little bit lost and because of that I have to say this time has come to an end and let you go.'
Nick then went on to say Brittany didn't have to say anything.
'I have a heavy heart right now,' he went on.
'You are an amazing woman. Trying to find my way in that cloud is too much for me right now.'
Nick went on to say that it 'wouldn't be fair' to enter into a relationship that 'a few months down the track could break her heart'.
Both Brittany and runner-up Sophie reacted with shock to the news.