It should be using the flash version from the safari browser which is the default browser in Mac OSX.if you are not worried about the preview, you should be able to work around the problem by disabling the preview.
go to WebAssist -> Preferences in the preview section, check the Disable preview option.

:-( Removed the preview by ticking the checkbox but still the preview and flash problem occur. Note also (see screenshot) the latest Flash is installed on Safari.
Also restarted DW to be sure the preference set.


