"I rang my girlfriend to help me and she sent her flatmate round," she said. "When we finally got them, because it took about an hour and a half, I said, 'I'd love to shout you a drink to say thank you.'
"When I walked into the bar there was Murray, so if I hadn't locked my keys in the car I never would have met him because I'm not usually a person who goes to bars."
Engaged in July, the couple had only days to re-enact the scene for the video competition before entries closed on Thursday.
"I saw it on Facebook about four days before the competition entries closed," said Ms Webb. "So we had a mad panic straight after Christmas as we were trying to organise everything to get it on track."
A professional videographer they organised cancelled at the last minute because of a funeral, and a dreary weather forecast made them hurry to the beach on their own horses, with a friend filming from the back of a quad bike.
"The way that we did it was exactly how it happened, word for word," said Ms Webb. "Murray organised this surprise ride on the beach as a birthday present and I thought my big surprise was getting to go for a ride on the beach with him.
"But then he said, 'I have one more surprise for you and would like to know if you'd marry me."'
Mr Armstrong said the gesture took him out of his comfort zone.
"I'm not very keen on riding horses so I thought it would be a nice thing to do for her."
The couple hoped Kiwis would help them secure a dream wedding.
"I've always had a dream to go to Turtle Island," said Ms Webb.
"We don't have a sympathy story or anything like that, we are just a genuine hardworking Kiwi couple and we would always help anyone who needed help without a second thought and it would just be nice if something like that happened to people like us."
The couple have until 9pm tomorrow to gain the most "shares" of their video entry on social media.
Watch the video here:
Entry for Turtle Island Horse Riding at Sunset Beach on my Birthday from Aveael Webb on Vimeo.
Vote for Murray and Aveael here.
