Before the entire cast stepped on stage (previous to the screening of Black Panther) there was a DJ spinning some records. Here you can see a couple of videos of him dancing just before going on stage.
From Oliver Night (one of the DJ’s): twitter video
From BleedingCool.com: post with video
This is another short video of him dancing and on stage from instagram: instagram video
Another instagram video (and some photos) of Martin and Andy Serkis before the presentation.