[lmm]

I don't know about videos but I used spark in my last job to solve problems of "we want to run this linear algebra calculation on x00000 user profiles and have it not take forever". For me the big selling point is it lets you write code that can be read as ordinary Scala but which runs on a cluster. As much as anything else it's practical to get the statistician to review the code and say "yes, that is implementing the calculation I asked you to implement" in a way that wouldn't be practical with more "manual" approaches to running calculations in parallel on a cluster.