I should have responded earlier to this, but i think the best way to do it is first bringing out the "epic news" that jj2+ exists and how long it has been in development, then give a good mixture of gameplay bits (maybe there is old footage from jdc) + slideshowing some of the epic custom maps made. Basically a lot of short video shots. After that just introduce the main features like spectator mode, custom gamemodes, show a scripted level (forest wheel i recommend), improved CTF (messages from scoring, flagholder), pit levels, working TNT, 32 player servers. This last thing is probably hard to do, hopefully there is some existing footage from it, because it does capture jj2 as a massive community (eventhough it's not) it may still make people excited. although all of this could be part of an overall community contributed jj2 content video aswell.