It will help apps which require interaction from users, like google stadia's game streaming. for other use cases, I think one does not care even if the feed is delayed by few seconds.
I could not get this logic. Can you explain more? problem would have been, if he got that money before demonetization, or he would have bought lands/gold, even then , if money comes in bank, "blackness" goes away, no?
If you are just asking Algo and probably pseudo code, these questions might help, but if you ask to write the proper code with boundary conditions etc, that makes it difficult even if you know the Algo. Of course I am assuming that no one memorizes the code ;).