Here's the info from the video (I can't possibly say it better...):
The firefighter in the video is David Tree.
He said he was in the middle of backburning at Mirboo North when he saw the stricken koala. "I could see she had sore feet and was in trouble, so I pulled over the fire truck. She just plonked herself down, as if to say 'I'm beat'," he said.
"I offered her a drink and she drank three bottles. The most amazing part was when she grabbed my hand. I will never forget that."
Mr Tree and his brigade then received an emergency call-out to save a house, but minutes later Sam (The name the Koala has been given) was picked up by wildlife carers.
She is one of 22 koalas, 14 ringtail possums, several wallabies and eastern grey kangaroos that have been handed into Gippsland carers.
UPDATE! Sam is recovering in an Australian Wildlife Center. Thanks to our twitter buddy @NewPetZone for the update :)