You can get Flash to work in Firefox. Also made this a post to help people, but I'm not sure it will get seen
If you need flash to work in firefox in 2021 and beyond, In my case it's for development reasons,
find your mms.cfg, copy and paste the text below, and refresh
#
#
#
# Disable Automatic Updates
AutoUpdateDisable=1
SilentAutoUpdateEnable=0
# Disable prompts to uninstall Flash Player
EOLUninstallDisable = 1
# duplicate actionscript console output
# in browser's console for javascript
TraceOutputEcho=1
# Enable the AllowList feature
EnableAllowList=1
# Normally, the allow list blocks URL requests
# unless the url matches a pattern in the list.
# In preview mode, all requests go unblocked,
# but console output is written for each request
# indicating which pattern it matched or that
# no match was found.
AllowListPreview=1
# if you should choose to make AllowListPreview=0
# Pattern to enable Your Legacy Flash Web App:
AllowListUrlPattern=http://wa.zozuar.org/