James Pinegar of Orem, who was in the hospital recovering from a bad fall on ice and bladder cancer, was caught on tape singing to his wife, Colleen, 86, KSL-TV, Salt Lake City, reported Thursday.
The couple's family put the video online to share with the rest of the family and friends, their daughter Linda Whitaker, 60, said.
"That's originally why it was filmed. Not everyone in the family could come see him in the hospital and he wanted to share his feelings. I don't think he knew he'd get so emotional, he just wanted to share something with the rest of the family," Whitaker said.
Since being posted online in February, the video has been viewed more than 400,000 times.
"I feel privileged to have witness this moment. Thank you so much for sharing," wrote one YouTube commenter.
"I can't stop crying. This is so precious," wrote another.