UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:49.0) Gecko/20100101 Firefox/49.0

Example URL:
http://sa.display5.com/flashtest1/d5.php

Steps to reproduce the problem:
1. open page included here
2. re-loading of each frame content causes bright white flash
3. 

What is the expected behavior?
The frame contents should load without any interval flashing where white BG is appearing , view same page in FFox on any OS and no issue, no flashing between pages

What went wrong?
Bright flash white between refresh of contents of frame, does not matter if contents is image, text, video etc, always seems to appear

Does it occur on multiple sites: Yes

Is it a problem with a plugin? No 

Did this work before? No 

Does this work in other browsers? Yes

Chrome version: 53.0.2785.143  Channel: n/a
OS Version: OS X 10.10
Flash Version: Shockwave Flash 23.0 r0

Almost all Chrome versions on several OS do the same, Linux, Mac, Windows, Raspberry Pi etc