Basically, if a site drops during the download, JDownloader will wait 2 seconds then attempt to reconnect.
If a site drops five (I think) times within a download, it'll mark the link as dead and you'll have to manually resume it:-
How would I go ahead and say "I don't care how many times it drops, keep reconnecting". Apparently youtube (or my ISP) likes to drop me a hell of a lot so I can download ~ 50MB of a video before being dropped. The whole reason I'm using JDownloader and not youtube is because of this.