OSX native equivalent to jdownload (app to download files from various sites, streaming, etc.)

I'm using jDownload which is great from a functionality standpoint, what it does, does it great, has plugins to download files from a lot of sites, like youtube, megaupload, and the like.

But it takes too much to open, and when trying to stop a big list of downloads it most of the times hangs (at least on my machine), and it takes up a lot of resources, not to talk about the cumbersome user interface, which is the smallest problem.

Do you know any OSX native equivalent that can download files from sites like megaupload and youtube?