com.apple.medialibraryservice.xpc
Recently I notice that the application/service 'com.apple.medialibraryservice.xpc' was bouncing in my computer dock. I did a quick search on the internet to see what was going on. I wasn't able to find a firm answer.
I did discover that this was happening when I was importing some photos via iPhoto. Some of the import were movies and some of those movies were using the new 'Slo-Mo' feature on the iPhone 5s.
I am guessing that the application was bouncing because it was rendering the 'Slo-Mo' movies as it was importing them.