Drag Seekbar to Content Already Viewed

Hello everyone!  

I have a video on a slide where we want the user to be able to drag the seekbar to the portion of the video they have already watched, but not to be able to fast forward.  For example, if the video is 2 minutes in length and they've watched 1 minute, we want them to be able to drag the seekbar back to the 1 minute that they've already viewed, but stop it where they have to view it yet.  Is this possible?  I know there are three built in seekbar conditions, but none of them can do this.  Is there a trigger of some sort to allow this?  Or does anyone have any suggestions on how to make this work?

Thank you