Shadowlands Spoiler alert!
The cutscene plays right after you complete the Shadowlands intro scenario and escape the Maw. You will activate the Waystone located in the Maw to get to Oribos, the Eternal City, where the leaders ask you how you managed to escape the Maw. You place one Shard of the Helm of Domination on the table and a Death Gate with Bolvar Fordragon and other Knights of the Ebon Blade opens, as they arrive to Oribos.