If you can't watch it for one reason or another, Reuben basically tells everyone at the last 15 or so seconds of the panel VoD to turn off their phones before they show off a video from Capcom meant for the panel. For more context, Dan Southworth later commented that they can't talk about the footage they showed at the end of the panel until Capcom official reveals it.
Sounds like we're getting DMC5 DLC to me (especially with Gamescom on the horizon), but I suppose Capcom could throw a curve-ball. Either way, it's definitely DMC-related.
Sources: Dan Southworth (Facebook), DMC Subreddit