Just pulled latest swfdec git and got this from a page with an swf in it.

Unsupported movie property wmode with value "transparent"
Unsupported movie property quality with value "high"
Unsupported movie property pluginspage with value "http://www.macromedia.com/go/getflashplayer"
Program received signal SIGSEGV, Segmentation fault.
---Type <return> to continue, or q <return> to quit---
[Switching to Thread 0xb7076720 (LWP 7461)]
0xb75599ae in g_type_check_instance_is_a () from /usr/lib/libgobject-2.0.so.0
(gdb) bt full
#0  0xb75599ae in g_type_check_instance_is_a ()
   from /usr/lib/libgobject-2.0.so.0
No symbol table info available.
#1  0xb753e746 in g_object_unref () from /usr/lib/libgobject-2.0.so.0
No symbol table info available.
#2  0xb5023c7a in swfdec_gtk_player_set_missing_plugins_window (
    player=0xb1161a8, window=0x8bd1800) at swfdec_gtk_player.c:443
	__t = <value optimized out>
	priv = (SwfdecGtkPlayerPrivate *) 0xad8ada4
	__PRETTY_FUNCTION__ = "swfdec_gtk_player_set_missing_plugins_window"
#3  0xb50431e9 in swfmoz_player_set_target (player=0xb1161a8, 
    target=0xa4c0130, x=0, y=0, width=776, height=178) at swfmoz_player.c:532
	__t = <value optimized out>
	__PRETTY_FUNCTION__ = "swfmoz_player_set_target"
#4  0xb5040182 in plugin_x11_setup_windowed (player=0xb1161a8, 
    xwindow=31457281, x=0, y=62, width=776, height=178) at plugin_x11.c:159
	attr = {title = 0x1 <Address 0x1 out of bounds>, event_mask = 147214, 
  x = 0, y = 0, width = 776, height = 178, wclass = GDK_INPUT_OUTPUT, 
  visual = 0x5, colormap = 0xb503b8b4, window_type = GDK_WINDOW_CHILD, 
  cursor = 0xb1161a8, wmclass_name = 0xac80804 "\001", 
  wmclass_class = 0xbf8ffc48 "\210�\217���+\b���\n\004\b�\n�", 
  override_redirect = -1208634656, type_hint = 181972388}
	parent = <value optimized out>
---Type <return> to continue, or q <return> to quit---
	window = (GdkWindow *) 0xa4c0130
#5  0xb503f3d5 in plugin_set_window (instance=0xad8ada4, window=0xac80804)
    at plugin.c:365
	__inst = (GTypeInstance *) 0xb1161a8
	__t = <value optimized out>
#6  0x082bffd8 in ?? ()
No symbol table info available.
#7  0x0ad8ada4 in ?? ()
No symbol table info available.
#8  0x0ac80804 in ?? ()
No symbol table info available.
#9  0x000000b2 in ?? ()
No symbol table info available.
#10 0xb7e1768c in nsCOMPtr_base::assign_with_AddRef ()
   from /usr/lib/iceweasel/libxpcom_core.so
No symbol table info available.