SWF size (width, height) shows as 0x0 pixels has a subtle bug with SWF content. The First time you drag a SWF file to the video tab, the width and heigh will be properly read from the SWF file, but then immediately forgotten. This can be seen by looking at the Info Panel / Media, where it will say:
Flash: 0x0

This can result in odd behavior when playing back the SWF file, especially with certain stretch modes (such as “Actual Size”).

We will fix this in a later version, but in the meanwhile there is an easy workaround:

  1. Drag the SWF file(s) to the video tab.
  2. Wait until the thumbnails are visible (you may see a window pop open briefly).
  3. Select the SWF file(s).
  4. click the [-] button to remove them from the video tab.
  5. Drag the SWF file(s) to the video tab a second time.

The second time you drag them, the size will be properly remembered.

This bug has been fixed in version and later/

See http://iscreensaver.com/releaseNotes