I just started to download a 64 MB file via HTTP. After a few seconds I got the Astaro download progress screen. (Link: http://iptv.mercedes-benz.tv/upload/mixedtape/compilation/Mercedes_Benz_Mixed_Tape_23.zip)
I've configured the maximum filesize for AV scanning to 50 MB, so normally it should bypass the scanner and be downloaded directly.
Another 301 MB file correctly bypassed the scanner, so this does not occur all the time.
Regards,
Bastian