^ you'll need AVI, MP4 & MKV screencap support for a minimum.
have you thought about using the RS API at all?
maybe add a virus checker like scanner.novirusthanks.com for files below 20MB? (if that is possible) and have a checkbox with - Scan for viruses? [y/n]

i suggest keeping it user-friendly and not adding too many useless features.. the concept is good - don't ruin it by making it over-complicated. or, leave the extra features for contributors/VIP users..
SJshah Reviewed by SJshah on . Link Checker & File Preview service - rsPreview.net Rapidshare Preview & Link Checker What are we? We are a site that allows you to post "previews" of your files hosted at rapidshare for your users. These are generated on the fly from your rapidshare links and then cached on our servers. We also provide a link checker that works on all forums and sites. We are currently making plugins for everything so if you need one PM me and Ill see what I can do. Example: RAR file preview Rating: 5