Seeker Bar, Video Options, and Triggers, oh my! Is this a 508 Matrix?

For our orgs 508 compliance, I need to be able to trigger the start of a video using a 'play' button--easy enough.  We don't want to use the video player controls, because we don't want users to be able to expand the video or play the video Picture-in-Picture mode, so we turn that off (even though PiP still plays, but that is another issue).  What we have left is the seeker bar, which should be controlling the video as it is an import and part of the timeline. 

The issue is, when I use the video option to play the video When triggered, I can no longer fully control the video with the seeker bar.  I can start and stop the video with the seeker bar, but I cannot move forward or backward in the video.  And yes, this includes allowing the user to drag the seeker bar, and the option is checked in the slide properties.  And note, that if I set the video option to play automatically, the seeker bar works.  

Is this a contrary function or a glitch?  It is a challenge with 508, but we need this to function accordingly.  Any work arounds? Thanks for the time and effort!