A couple of services enable to create playlists of music videos hosted at YouTube. To be named there are TubeRadio.fm, MixTube or the music player software Muziic. Now YouTube has introduced an own playlist editor called Disco, which too is described by the long phrase YouTube Music Discovery Project and Playlist Creation Tool.
The service is most comfortable. Beside the broad availability of music videos primarily this concerns the fast search facility. A bit problematical is the handling of videos regarding global legal aspects, which in the case of unavailability at a particular country has led to flickering while using the service. If this happens, it may be recommended to delete the playlist and to add music videos manually.
Similar services are available at music videos.