YouTube is making all its videos interactive. Uploaders can add another 'layer' to which the creator of the video can add interactivity. You can also add, for example, text balloons. This allows people to select a gaming-form, for example with cards. Depending on your choice, a different movie will start up (demo video). In this sense, the interactivity is limited and it exists, in fact, of a script.
Future Vision by Erwin Van Lun on this article
People have always responded to video. Just look at their faces when they’re watching. They feel, think and do all sorts of things. Except that the screen doesn’t respond to that. That’s changing slowly. Now the creator is able to add a layer. Soon this will be a 3D world in which something happens by default (call it a movie), but if we want to participate we can do this too. Because YouTube is picking up on this, this development is clearly a step closer.