So audio-only and playlist embedding were broken due to changes at YouTube’s side, but version 1.1.4 fixes that.
Some information for those users that implement WP YouTube Lyte’s audio-only embedding feature; it got broken because YouTube started to enforce the minimal player size they recently added to their TOS. Audio-only is, for many reasons, something that YouTube doesn’t want to support and indeed might even want to block, so this might break again. So if you want to be on the safe side or if you just don’t want to piss YouTube off, you probably should reconsider doing audio-only.
That being said, here’s a nice audio-only track for your audio-only ears to celebrate this new release;
(Rahshaan Roland Kirk -- Spirits Up Above)