http://superuser.com/questions/726789/flash-files-swf-prompts-for-download-instead-of-opening
Apparently, the problem was with the MIME type used by the browser to open the files.
The workaround to resolve this is to
edit the
sudo leafpad /usr/share/mime/packages/freedesktop.org.xml
/usr/share/mime/packages/freedesktop.org.xml file from:
<mime-type type="application/vnd.adobe.flash.movie">
to:
<mime-type type="application/x-shockwave-flash">
and then run:
sudo update-mime-database /usr/share/mime
Some users needed to reinstall the flash player as well.