SWF to Animated GIF will allow you to drag and drop any SWF file into the program or select a SWF with the "open file" option.
You can capture multiple frames from the running SWF, use the current frame number to select a frame.
You can drag the captured images to your desktop as 1 animated GIF (if there are multiple frames) or use the save button. GIF is the only format supported at the moment.