Need Movie Player Advice

How can I make a feature on my Flash video player that keeps track of how many minutes of the video is watched by each IP address?

For example, I want to keep track of how many minutes of video is watched by each user. Basically all I want is for the player to send out a signal every minute of video played so that I can subtract a minute from that user's 'total minutes'.


Any idea how I can do this?

Thanks!