I had a problem with two players on the same page using widgets: when pressing on a thumbnail both players started playing the video.
I also made the solution which maybe could be included in a future update: in script.js the variable f is called, but this refers to all players.
Adding the following f = to the existing click function in script.js:
f = $(this).closest('.widget-container').find('.vmcplayerdiv iframe');
will solve the problem.