Questions[swf](ubuntu)

I created a .swf file and want to play it on my computer. At first, I realized I did not have Adobe Flash for Firefox, so I installed it this way. Then, I tried playing the .swf file again, and now the following message shows up

application/x-shockwave-flash decoder is required to play the file, but it is not installed

I looked it up on the Ubuntu Software center but could not find it. Could somebody tell me how to install it? Here is some info about my computer

EDIT: At first, I tried opening the file with the default video player on Ubuntu and this is what appears. Afterwards, I tried opening the file using Firefox and now this appears. Every time I click on "Ok" another tab is opened with the same message.

I am new to Ubuntu, running 16.04, so forgive me if I've overlooked something simple or obvious. I've been on this thread How do I play .swf files? but nothing there has worked for me.

I installed gnash but it only displays a blank screen when I try to play the .swf file.

I tried the Adobe Standalone Flash Player, but it only asks for a url. I can't determine any way to play the .swf saved on the computer - the player is not an option under 'open with'

When I tried the Edit /usr/share/mime/packages/freedesktop.org.xml file option, when I found that file, it opened in my firefox browser and I could not edit anything.

When I try to open the file directly with Firefox, it just asks what program I want to use to open it. If I choose Firefox, it opens another tab with the same question, again and again.

VLC media player will not play the file.

What else can I do?

on ubuntu 14.04 forefox won't play swf even though flash is installed. I tried editing the mime type file and updated the mime databse and still get nothing.

Before I upgraded to Maverick, .swf files used to have a thumbnail in Nautilus. However, Nautilus doesn't generate thumbnails for them anymore, even after removing ~/.thumbnails/, which most likely indicates that a package is missing.

How do I get Nautilus to generate thumbnails for .swf files?

EDIT: I've added a bounty, as I believe this question might still be answered...

Does anyone know what libraries I have to install to play .swf files?