Do schools accept online doctor certificates?

You know that site updoc where you put in your symptoms and pay for a medical certificate? Is that accepted for a Victorian employee?

My regular doctor is fully booked till next week.

I had to take the day off because I have the flu really bad. Since yesterday was a public holiday, I will definitely need a certificate.

So before I pay, has anyone else used this site before? Sorry if this sounds like a silly question, I have just never used a site like this before.