YouTube videos with separated audio

[suadnovic]

I use JDownloader and Internet Download Manager (IDM) for videos from YouTube.
In JDownloader window I have this

and it's useless to downoad, because I can't play this on XP. And IDM, which is integrated in Firefox dont offer to download it, as usual.
I don't understand what it is about and how to solve it. Can somebody help, please?

[oss]

use youtube-dl

[suadnovic]

Thanks, worked.