Update, downloaded the .swf file and uploaded it to VirusTotal, scan in progress now and so fare only avast has detected it as infected. VT just failed at 23 scanners an only avast detected it, I will upload again and see if it completes, but it looks certain it is an FP, I have submitted it to avast.
As a temporary measure, you could add the path you posted to the Web Shield, Customize, Exceptions, Add. This will exclude the file from scans.