Really good question.. And we can only guess what happens in scenarios like this. My guess is that they sent the rest of the unit or another unit to the original fire.Y'know, that makes me wonder... Do firemen have a triage system like hospitals? The truck in the vid had his lights on, which makes me think they were on their way to another fire... But what if the other one was more dangerous/out of control than this one?
Of course, just letting those people there with their car on fire also seems like a very bad idea, but still...