AirTime is Facebook’s Hangout. Of course it all makes sense. Video is the final frontier. Same with meeting those you do not know, live. Chatroulette (remember that?) proved to be a great MVP for that market. And of course Sean Parker being a major shareholder in Facebook makes the alliance much more concrete. The deep integration with FB will certainly be crucial.
PPS: For the copycats out there, you could still move fast and do something similar with Twitter. The difference is while AirTime will be focused on Facebook’s people graph, one built upon Twitter will be based on their interest Graph.