I found out a weird behavior on my FileMaker solution.
Let's say there are 2 ways to insert a file into container field:
(1) Drag and drop to container field
(2) Use insert file script and target container field
The playback feature is not working if the file is inserted via method (2). The same exact file will show preview if it is inserted by method (1). I tried with both png and pdf. Not sure if someone else here shares this issue, here is my build: