All .js and .jsx files are listed in the Scripts menu.
The SimpleViewer.jsx file (listed as 'SimpleViewer') is the actual plugin and it is this entry which should be selected.
The 'simpleviewer.js' file can be hidden from the Scripts menu by prefixing it with a ~ characters. Then, only 'SimpleViewer' (the actual plugin) should be visible.
Go into the plugins's 'svcore/js/' folder and do the following:
(1) Rename 'simpleviewer.js' to '~simpleviewer.js'.
(2) Rename 'swfobject.js' to '~swfobject.js'.
I have now added this information to the Upgrading the Photoshop SimpleViewer Script support page.
SimpleViewer Support Team