"Image songs" for the main characters (Yusuke, Kuwabara, Kurama, and Hiei) played over highlights of their greatest battles .
The (映像白書) series is a collection of Original Video Animations (OVAs) that primarily serve as retrospectives, music video compilations, and brief epilogues to the original 1992–1995 anime series. While the original Eizou Hakusho episodes were released in the mid-90s, the "2021" designation in your query likely refers to a digital re-release or fan-encoded high-definition rip often distributed in MKV format following the series' 25th-anniversary celebrations. Overview of Eizou Hakusho Content yu yu hakusho eizou hakusho ova mkv dvdrip 2021