What flash players are you using to play the swf without a browser?
I'm using the official flashplayers, got them from archives, but you can also get them directly from the archived adobe website with a bit more work
Get the original standalone flash player from the source
directly from the source so with no virus risks,
go to the archive of all the adobe flash urls downloads under
http://fpdownload.macromedia.com
That is
https://web.archive.org/web/*/http://fpdownload.macromedia.com/get/*
On the search box on the right "filter results by" type ".zip"
You'll get the list of all the archives for flashplayer installation, you can sort them by archive date or by link name
The zips contain all the versions of flash for all the operative systems, for windows, linux, mac. The zips are a bit burdensome, and the download from web.archive is slow.
Inside the .zip, among the .exe for windows, there are usually three versions, with this naming pattern:
flashplayerXrYYY_win.exe - is the installer for flash in the browser
flashplayerXrYYY_win_sa.exe - is the stand alone flash player, it requires no installation and it's ready to use
flashplayerXrYYY_winax.exe - no clue what that is
Archives of the original standalone flash player
Some of these archives used to work before the web.archive hack and crash, but have become unusable since then, and seems to have been removed by censorship
https://archive.org/details/flashplayer-11
https://archive.org/details/offline-flash-player-installers
Given this trend of scrubbing any archive of the flash player executables, it's advised to download them for safekeeping even if not for direct use, flashplayers from v11 to v32 are fine
These are the archives currently working, but given what happened with the above, get your player before those get scrubbed too
https://archive.org/details/standaloneflashplayers
https://archive.org/download/standaloneflashplayers/fp/
https://archive.org/details/Adobe_Flash_Player_Complete_Collection
https://archive.org/download/Adobe_Flash_Player_Complete_Collection/fpdownload.macromedia.com/get/flashplayer/installers/archive/
This last one is a complete copy of fpdownload.macromedia.com as shown in the first method
Other standalone flash player
Some suggested also globFX swiff player
https://www.globfx.com/products/swfplayer/
That one requires an installation though, it's not ready to use like the original