Some people only use one download manager and it's nice that jD can download http links as well.

The http links can be disabled in Settings -> Plugins & Addons -> Host.

HTTP and FTP are the protocols supported by jD.

The name "http links" is indeed confusing, but what do you suggest?

I believe most downloads are video or audio. Why shouldn't jD download these?

Can you please explain or rephrase your last sentence, because I don't understand it?