Plot Background Explained (Includes spoilers)
I did not understand the plot when I first saw the film but this site (link below) provides helpful background. I plan to watch the film again with this background in mind.
There are spoilers in the link below but they may be necessary to follow the movie.
http://mikefahey.blogspot.com/2015/09/cheat-sheet-for-hou-hsiao-hsiens.html