Question   Under what circumstances would contacts have a score of 0?

A. The score as an indicator to how active the contact is.

A. From advanced features page

A.

• View a page
  
• Open an email
• Click a link in an email
• Invite a friend
• send a chat message
• log into chat
• log into page
• watched video

A.

(SMS Marketing Tool Required)

SMS notification sent to the member once a contact exceeds a specified score.
to set the score value
1- Go to Advanced Features

2- SMS/Voice Broadcaster

3- Set Contact Score SMS Notification
Now each time a contact exceeds score points, SMS notification will be sent to the member using member credits

Following documents explaining how to setup Twilio
Learn How to Setup Twilio

A. If in the editor the video is setup as a video (not WYSIWYG but the option that is specifically for videos) AND if an mp4/flv video is used then it tracks the percentage of the video watched and adds it to the scoreboard.  You can edit the amount of score awarded for watching a video under advanced features.

An alternative way to do this is to setup a delayed action when editing the page.  When doing a delayed action you specify an amount of seconds the person has to stay on the page and then once the time has passed something happens (like they have points added to their score, or their contact group changes).