As other posters have noted, there are some advance Scala features being used here. It's almost important to note that this talk was given at Scala Days, a conference for Scala programmers, so presumably the target audience is all ready expected to be familiar with Scala (and its syntax). Additionally, given that the speaker appears to be giving reasons why Scala can be a better choice than Ruby, his intended audience may be even smaller: Scala enthusiasts working at a Ruby shop who are trying to convince their coworkers/management to transition from Ruby to Scala... :P