Firefox 49.0. flash player 23.0.x (tried version 19 Sep 16 and 04 Oct 16) on Mac OS 10.10.5.
ALWAYS crashes when using ANY flash website. Your version released 04 Oct 16, in fact, hung and resulted in an unresponsive machine! Used uninstaller and reverted back to V 22.0 At least that works.
Apparently, this is a "known issue" since August 2016
It appears that: Re: Plug in Failure applies (as per below post).
May I say, though, that it is peculiar that the issue was already know, yet an update was issued a month after and it is still not fixed. Not sure what happened here. Thank you.
This issue is fixed in the latest release 18.104.22.168, released today.