The defector, who ran across the border at the Panmunjom truce village on November 13, was shot at least four times and has been recovering in a South Korean hospital.
The footage released by the US-led United Nations Command (UNC) showed one soldier pursuing him across the military demarcation line (MDL) for several meters, before hesitating and turning back to the North.
The badly injured defector was then pulled to safety by three South Korean soldiers who crawled to reach him just south of the dividing line.
It is very rare for the North's troops to defect at Panmunjom, a major tourist attraction and the only part of the border where forces from the two sides come face-to-face.
The footage began by showing the defector's vehicle travelling at speed along an empty road leading to the truce village before stopping near the heavily armed border.
UNC spokesman Colonel Chad Carroll told journalists that the footage showed one of the border guards "run across the MDL a few seconds before returning back to the north side of Panmunjom".
The UNC has "requested a meeting to discuss our investigation and measures to prevent future such violations," he added of the incursion which contravenes a 1953 armistice agreement.
The UNC has conducted a "thorough" investigation of the incident, he said.
"The key findings of the special investigation team are that the KPA (North Korean army) violated the armistice agreement by 1) by firing weapons across the MDL and 2) by actually crossing the MDL temporarily," he added.
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