If you copy the link and FlashFXP attempts to connect and doesn't get in because the site is busy, if you then exit IE, FlashFXP will attempt to connect once more and return a 'Connection failed (10038:Socket operation on non-socket)' response.
I don't know if it was because I did something wrong, I created an .htm file with just the following lines to test the clipboard monitoring function:
<html>
ftp://login:password@site.goes.here.com:1234
</html>
of course, with all the correct info in the right places.