Solution: Copy NPSWF32.dll from C: \ WINDOWS \ system32 \ Macromed \ Flash \ to the C: \ Program Files \ Mozilla Firefox \ plugins \ folder.
Upgrade Flash Player to the latest version.
Flash Player 10 Debugger download
Flash Player 10 ActiveX control content debugger (for IE) (EXE, 2.12 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/10/flashplayer_10_ax_debug.exe
You can use this in IE.
Usage: Put the downloaded flashplayer_10_sa_debug.exe under the C: \ WINDOWS \ System32 folder.
You can run Debug normally.
Flash Player 10 Plugin content debugger (for Netscape-compatible browsers) (EXE, 2.09 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/10/flashplayer_10_plugin_debug.exe
This is used by Firefox.
How to debug flash player in Firefox
Install the plug-in for Netscape-compatible browsers or
Copy NPSWF32.dll from C: \ WINDOWS \ system32 \ Macromed \ Flash \ to the latter folder C: \ Program Files \ Mozilla Firefox \ plugins.
Restart Flex Builder and select Firefox in Window> Preferences> General> Web Browser.
Flash Player 10 Projector content debugger (EXE, 5.18 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/10/flashplayer_10_sa_debug.exe
Flash Player 10 Plugin content debugger (Intel-based Macs) (6.31 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/10/flashplayer_10_plugin_debug.dmg
Flash Player 10 Projector content debugger (ZIP, 6.22 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/10/flashplayer_10_sa_debug.app.zip
Flash Player 10 Linux debugger and standalone players (TAR. GZ, 16.3 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/10/flash_player_10_linux_dev.tar.gz
Flash Player 9 Debugger download
Flash Player 9 ActiveX control content debugger (for IE) (EXE, 1.61 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/9/flashplayer_9_ax_debug.exe
This is used by IE.
Flash Player 9 Plugin content debugger (for Netscape-compatible browsers) (EXE, 1.57 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/9/flashplayer_9_plugin_debug.exe
This is used by Firefox.
Flash Player 9 Projector content debugger (EXE, 3.73 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/9/sa_flashplayer_9_debug.exe
Flash Player 9 Plugin content debugger (Intel-based Macs) (6.31 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/9/flashplayer_9_plugin_debug_ub.dmg
Flash Player 9 Plugin content debugger (PowerPC-based Macs) (DMG, 3.39 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/9/flashplayer_9_plugin_debug.dmg
Flash Player 9 Projector content debugger (ZIP, 4.68 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/9/sa_flashplayer_9_debug.app.zip
Flash Player 9 Linux debugger and standalone players (TAR. GZ, 9.36 MB)
Http://download.macromedia.com/pub/flashplayer/updaters/9/flash_player_9_linux_dev.tar.gz
Flash Player Debugger official download page:
Http://www.adobe.com/support/flashplayer/downloads.html