"I don't think the number is that large," he says. "But there must be many."

Every video receives comments supporting him but also expressing concern about volunteers' safety.

Many reminded him to wear his mask properly after he once failed to do so.

Volunteers transport materials ranging from medicines and masks to bottled water and instant noodles.

They're aware of the risks.

"Someone has to take on this duty," volunteer Zhou Yiyu says in Lin's vlog. "We come to help, not to face doom."

Drivers park away from hospitals to unload from safe distances. They wear protective suits if they must go near.

Another unnamed volunteer, who appears in the vlog, says: "It's natural for us to occasionally feel fear. But we have nowhere to hide or escape to. Wuhan is our city."

Lin's videos show how other good Samaritans contribute.

For example, hostel owner Xiao Yajuan allows medical staff to stay in her place for free. The hostel has, in turn, become an information hub.