Elusive Dash Rattle

Hi PriusChat,
As my username suggests, I have a rattling problem with my 2011 Prius and I was hoping you guys could help me out! Here are the quick facts:

• The rattling typically happens while going over bumps or driving on patchy roads. It happens when running over the "buttons" on the road.
• The noise is not related to RPM, or transition from battery to engine usage.
• If I had to describe the noise, I would call it a "plasticy" buzzing/ticking.
• It definitely sources from the driver side dashboard. Passengers cannot hear it well.
• This is a video of the rattling.
• I have tried pressing down on various panels, none seem to eliminate or dampen the sound completely.
  
• However! Smacking the light-gray panel below the "triangle window" use to temporarily reduce the noise.
• 
• I've tried removing the same panel below the driver side "triangle window" because I thought the noise was coming from there but it persisted.
• I read on another rattle thread that the column supporting the roof (and bordering the triangle window) is the real culprit, but punching it only reduces the rattle sometimes.
• I've brought it into my local Toyota and they did a search for anything that could be rattling. They didn't help, and after they finished the center console was rattling too (which I've fixed).

Any help would be greatly appreciated, please let me know if there's any more information I can give!
Thanks guys!


EDIT: Also, cold weather seems to worsen the symptoms. I should also state that sometimes I have little to no rattling, but on other trips there is no end to the rattling.