All we know duckload was became popular in recent days it will also allow to download unlimited with high speed and resumable links. but only problem with it is some times it doesn't support to download with IDM mostly after first download. Here is the solution for it you just need to add an add-on called FlashGot, it is absolutely free.

Go to this link from your mozilla firefox and you get add-on to install then install it and restart your firefox browser. It will not work in any other bowsers. 

 Mozilla Add ons

https://addons.mozilla.org/firefox/downloads/latest/220/addon-220-latest.xpi?src=addondetail