The song goes on to include a promise that he would give his heart to Nelli if she treated him “like a king”.
The couple got engaged earlier this year, and AKA met Nelli's family for lobola negotiations a few weeks ago.
The video has been viewed more than 2,000 times since it was posted. AKA also dedicated his hit song Cross My Heart to Nelli.
That song includes the words “I can't get you out my mind ... Every time we say goodbye. I wish that I held you more. Inside. Harder, Better. Faster, Stronger. Absence makes my heart grow fonder”.
On Sunday afternoon, Nelli and AKA's families issued a joint statement confirming her death.
“We are still in shock and dealing with our emotions as she was an exceptional and gifted young woman with so much life ahead of her. She had a sweet nature and was always nurturing to those about her.”
The statement said AKA “is now inconsolable and is surrounded by family and [his] closest friends”.
Police have confirmed the incident was under investigation.