While this video is getting passed around the internet because it is adorable - it's important to note that stairs can become a legitimate fear for a dog if a puppy is not exposed to them while they are still young. This is true with various surfaces (street grates, linoleum, sand, etc) as well. If you don't push puppies into all these new experiences, then you're going to be calling me when your puppy is an adult, because they have developed a phobia that is getting in the way of their life and your life.
This is especially important to consider when purchasing a dog from a breeder. A good breeder will expose a puppy to new situations, people, and dogs at an early age to prevent these phobias. Many will even have a dog potty trained before you bring your new pup home! If you find that the breeder you're working with does not provide these types of services, consider finding a different one. It will save you time and money in the long run!