The touching video comprised of photos and footage of their life together made Robert realise he didn't want to throw their relationship away.
A friend of Kristen, 22, told The Sun newspaper: "She sent Robert the film after bombarding him with hundreds of texts, emails and answer phone messages.
"It was a last-ditch attempt at getting him back and she spent ages making the video montage using hundreds of photos and hours of home film footage of nights out and holidays."
It would seem that Google Chrome's recent advert - which sees a man begging for his ex-girlfriend's forgiveness through a film -inspired the actress as she chose the same approach to try and gain Rob's forgiveness.
The source added: "It was just like the Google Chrome ad as she cut-and-pasted lines from love poems to connect it all together."
The pair have been spotted out several times since they got back together, most recently at a Prince concert in Los Angeles last week, and Kristen recently spoke about how she has learnt from her mistake.
She said: "You have to be OK with your own fears. If you're an honest person you'll make mistakes, but it'll be OK. The most interesting things happen after making mistakes."