I'm not familiar with the app but I am familiar with the practice- One of my favorite dharma talks is called True Insight given by Genjo Marinello, the abbot at Chobo-Ji in Seattle- He's a psychotherapist by profession-
Try Headspace. The narrator has a nice voice (British) and is a good introduction to mindfulness. There are some little clips to watch and then you can just listen through headphones to his directions.