As two men walked by an apartment complex, they noticed the child on a window ledge four stories up.
The one-year-old teetered on the edge, and then fell.
Both men are seen raising their arms as they move, trying to judge where the boy was falling.
"I didn´t think too much at the time. I was just afraid of failing to catch him," one of the men identified only as Li, told a Guangdong, China TV station.
Jumping a step forward at the last second, one of the men cradled the child safely into his arms.
Millions have seen, and commented on the video via YouTube. "Wow, that is what I call nice catch! That guy is a hero!" one wrote.