Avast reports malware from that altervista link. Avast also reports YTDownloader as adware from other various download sites. I strongly suggest do not use YTDownloader as its widely reported, for some time now, to be malicious (may also be involved with Goobzo accelerator). http://youtubedownload.altervista.org/respect_ip.htm http://www.herdprotect.com/signer-greentree-applications-srl-55a7f018b18d4b6488fe25e1e6d2af31.aspx I use Flashgot FireFox plugin for downloading Youtube/flash related videos. https://flashgot.net/faq#qa2_1