Also, What about adding a list of known junk/virus files with their sha1 as an option. I believe LW collated such a list & in the recent LW 5.2 release, LW deletes any such files upon completion of downloading. This prevents the files being re-shared & protects the downloader. However, such would be better if they were immediately blocked from search results or blocked from downloading or flagged as being known 'unsafe' junk. Where to get such a list? I am sure some of the trusted supporters of Phex could collate such a list.

Whilst jofan suggested the junk's sha1 change from week to week, there are still known older ones out there.