Hi,
For your question:
When app is compiled from old builder and installed on device, video plays OK.
My answer:
Yes.
For your question:
But when you export app from upgraded builder and install on device, it doesn't play?
My anwser:
I did not export to device, but scanner the QR code and open it in mobile browser. the video can not be played.
if I simplified the page by give a constant value to "src", it can be played on mobile browser, but when I tried feed src using localStorage.getItem, the video failed to play, I can ensure the value is OK, because when I open this page in PC browser, the video can be played with no problem.
for mobile device, I am using samsung GC100 running android 4.2.
hope this helpful.