Automatic Frame count

Hi. I heard somewhere about a field related to versions called Frame Count wich supposedly tells you how many frames does a published video have, as opposed to how many frames the scene should actually have.

Now, as I looked for Frame Count I found that is empty and I can fill in the info. It was my understanding that the field should be somewhat automatic, like an Audit Field. Can anyone shed a light on this subject?

Can anyone please help us out here?