The woman identified only as Grandma Chuam apparently suffers from Alzheimer’s disease and had been secured to prevent her wandering from her home.
Her stepsister Wimol, 65 (surname withheld by the authorities), who shares the house in Moo 6, Phanom Sarakham district, had arranged for a young neighbour to watch over Chuam while she went out on an errand.
The man, alarmed by the scene, took several videos as he attempted to free her and posted the clips on Facebook on Wednesday.
Within the first 19 hours, one of the clips had been viewed 1.98 million times, drawn 19,000 reactions and been shared 53,000 times.
District chief Thitirat Sangngam was at the house at 9am on Thursday and learned from Wimol that Chuam had no children and was suffering from dementia, often wandering off outside.
Late last year Chuam was found sitting in the middle of a rice field amid heavy rain.
Thitirat said authorities would replace the house’s missing door and add a room where Chuam could stay secure without the need for chains.