I need to change the look an feel of the playlist carousel. Is it possible to show the playlist carousel on mouseover during video playing?

You can enable the onPlay Carousel and set auto-hide=true for control
bar, which affect on the carousel (Playlist)

UI => Controls tab => Thumbnails => Show Thumbnail Carousel on Play
UI => Player tab => Control Bar => Bar Auto-hide

The carousel will reveal itself on mouseover during playback.
Also you can change the size of thumbnails

UI => Controls tab => Thumbnails => Thumbnail Height
UI => Controls tab => Thumbnails => Thumbnail Width