Sorry but I beg to differ, the malware-gen the -gen indicates generic signatures, which have proven very effective in detecting hacked sites in the past, though that is normally seen as win32:malware-gen or win32:trojan-gen and further analysis of the page has found either iframe tags added to the page or javascript with obfuscated code.
However, that page appears not to be a normal web page.
So I don't think we can make that false positive statement, it needs further analysis. Uploading it to virus total shows this has been scanned before 17/7/2008 and only two AVs detected it, Cat_Quickheal and Nod32, they both detected it as SWF.Exploit (Shock Wave Flash Exploit) which would possibly account for the other:malware-gen name given by avast.
A fresh analysis shows now, avast and GData (uses avast as one of its engines) detection as other:malware-gen with the original two detection still the same swf.exploit.
http://www.virustotal.com/analisis/f452eeb26fda95c2c654638299f744c7With only 4 (3) of 36 (35) detections on VT it could possibly be an FP and should be sent to avast.
Edit: Sample sent, now we wait.