DESCRIPTION:
I apologise that I can't reply to any of your questions, mostly because there's no reply button option under your comment.
1.What's the name of the app?
"SuperStar SMTOWN"
2.How to download the app?
Search "Superstar SMTOWN download tutorial" into google and it'll give you a bunch of links.
However this tutorial is also useful, credit to this person;
http://onehallyu.com/topic/109441-superstar-smtown-tutorial/
3.How do I record the game?
I used a screen mirroring app "Reflector" and it is available for windows or mac which you can connect your phone with the computer/laptop

music credit: SM entertainment