A group of young people hiking in the Bekaa Valley in December took the mobile phone video from a distance, in which a small cub can be seen running around in the snow with its mother.
The cub is estimated to be less than a year old, as after that offspring fend for themselves. It is thought the bears must be responding to unusual cold or a threat to be active during the winter.
The video has excited conservationists as it marks the first sighting of the species in the country since 1958. The nearest other known location for the bear is 300 miles (500 kilometres) away in Turkey.
Assad Serhal, director general of the Society for the Protection of Nature in Lebanon, called the finding “historic” and a “positive development”.
The Syrian bear was first identified in Lebanon in 1828, but changes to its habitat and excessive hunting drove the species to extinction about 100 years after it was first discovered.
There are just one female and one male left in the country at a reservation in the Chouf mountains. Attempts to get the pair to mate have been unsuccessful.
The Syrian bear, one of 16 types of brown bear worldwide, lives in mountain ranges across the Middle East. Its conservation status is generally classified as vulnerable in Iran, Iraq, Turkey, Azerbaijan, Armenia, Turkmenistan and Georgia, but the species is officially extinct in Lebanon, Israel, and as of 2009, in Syria.
In winter it hibernates in caves and tree hollows at higher altitudes, and in warmer months forages for food in grasslands and forests.
The sighting has delighted Lebanon, where the video has been widely circulated on blogs and in news reports.
There are now calls for the Ministry of the Environment to make sure the area the bears were found is protected to ensure their safety from hunters.