What can you use instead of a hammer?
If it’s a thin picture nail, thumbtack, pushpin, or similar, a makeshift hammer will work just fine.
How do you hammer nails without hitting your finger?
Quote from the video:
So what you want to do is get a little bit of blue tack. And push your nail through the blue tack. And put it in the right position there on your bit of wood. Like that and start hammering.