How about providing the steps to replicate the issue. Is there a reason for that version of Firefox?

steps :

step 1. install joomla 1.5 on xampp 1.7.1 with php 5.2.9 on windows 10 64bit.

step 2. download and install Mighty Resources for joomla 1.5 here . they are all for free. http://www.mintjoomla.com/download/mighty-extensions/item/3640-mightyresources.html

step 3. create a section and a type for the mighty resource in joomla 1.5 backend.

step 4. create a media field for the created type for mighty resource in joomla 1.5 backend.

step 5. now create a link in joomla 1.5 menu admin to the section created for mighty resource for joomla frontend.

step 6. now test the media field in joomla 1.5 frontend . Flash Content does not show completely here as mentioned in the images provided in the first post .

We are using Firefox Developer Edition version : 84.0b8 (64Bit)

Firefox doesn't run the Flash plugin in versions released in 2021, so I don't think anyone here can test problems with Flash running in older versions of Firefox -- unless they have a system that has not yet been purged of Flash.

Can you switch from using Flash to using standard HTML for your media player? There must be a Joomla plugin for that, or see: https://developer.mozilla.org/docs/Web/Guide/Audio_and_video_delivery/cross_browser_video_player