During the cold war a German friend told us the story of the old man in the East who wrote to his son in the West "Dear son, I think the Stazi are reading my letters, so I am putting one of my old grey hairs in the envelope, if it is not there you will know it dropped out when they opened it"
His son wrote back, "Don't worry father, I found your hair"
So then the father knew his letters were being opened.
Actually I don't know how far in you put the slip, but it is quite normal to make a decision on the first page or two, after all, most people looking at books in a shop only read the first couple of paragraphs before deciding whether or not to buy.
Why not? There is a huge amount of stuff there to choose from. Not just 'look at this silly video', but classical books and music, traditional stories, all sorts. It is great for the 'Damn, I can't do this' moments, from fixing the car to accessing the printer. There is someone on there who will talk you through it step by step. Go on, click my link, you might enjoy some of my stories.