Amy Hawkins' rendition of the popular World War One song It's A Long Way to Tipperary was captured by her great-grandson on her milestone birthday.
Since then Sacha, 14, has clocked up 100,000 views of the video.
Ms Hawkins, of Monmouth, was a performer and at Sacha's age toured the UK - but her mother banned her from the stage, as it was not "respectable".
Sacha's mother Hannah Freeman, said the reaction to the video on the social-media site has "restored faith in humanity".
Ms Hawkins, aged seven at the end of the war, has sung songs from that era ever since.
She's like a clock, once you wind her up she won't stop. She just keeps asking, 'Would you like another one?'," said Ms Freeman, her granddaughter.
Ms Hawkins was touring with a dance group when her mother banned her from such a career.
She now lives with three other generations of her family and Ms Freeman said they "feel very lucky" to have been able to spend lockdown together.