Good webvideo download app?

[The_Prodigy1982]

On my previous Windows computer I used Internet Download Manager, which worked absolutely great for downloading video's from YouTube and so on...

I'm now looking for the same kind of app, but for OS X.
I already checked out Xtreme Download Manager AND Wondershare YouTube Downloader, but both don't work properly.
Do you guys know any good ones, that actually DO work?
(they need to support as many formats as possible)

Thanks!