An interactive queue video posted on today's Disney Parks Blog.
Yesterday on InsideTheMagic facebook page, we see the special SDMT MagicBands that were handed out to the press for the 3-day Preview Event going on now.
Also yesterday, Disney released a near full-ride video of the coaster, though some key elements still were not revealed.
This from InsideTheMagic: It's been confirmed--the Mine Train will NOT officially open after Friday’s dedication. Official date TBA, likely late May. (Unannounced soft openings always possible until then.)