The video titled "Crackhead lights hair on fire" posted to the LiveLeak website was apparently filmed Sunday in a downtown bar district and has generated more than 50,000 views.
The smartphone-quality footage shows a man flicking a lighter by his right ear while young men off screen are heard egging him on.
The man hardly responds when the back of his head bursts into flame, while at least one person urges him to stop as others laugh and the man pats out the fire with his hand.
Homeless advocates say the act is exploitation, while non-profit Megaphone Magazine calls it "horrible and disgusting," noting it's not the first time such an incident has occurred in Vancouver.
Const. Brian Montague said that although the video is disturbing, there is no overt force from another person suggesting assault though the video has been forwarded to investigators.
"With the short video only, it is difficult to say this is criminal in nature at this time," Montague said in a statement.
The video appears edited, is incomplete and does not show what happens before the man's hair goes up in flames, Montague said.
He said it's hard to determine from the video alone if someone has coached the man, offered money or put him in any duress.
The 30-second video ends with someone handing the man a cigarette, which he takes, possibly as a way to get him to stop, Montague noted.
"It is unfortunate that there are those that think it is acceptable or amusing to watch, film and post," he said. "Especially when it involves someone who is clearly part of a marginalized community."