Do a lot of people use HTML5 Boilerplate for projects?

Actually, most people who do this for a living use boilerplates, either open source ones, or ones they've developed themselves along the way. (I know I do. I like writing code I can re-use later on in other projects.)

While being able to build something from scratch certainly indicates you know what you're doing, it's also a waste of time when doing (large) projects. You want to develop as quickly as you can, and that sometimes means using boilerplates, templates, code snippets and so on.

That's one of the differences between learning something and doing something for a living. When you're learning, you want to do everything from scratch just so that you're sure you understand everything. But when it's a job, you just want to be as agile as you can be.

I watched part of that you tube video. Looked pretty cool to me. Here, we learn how to do things from scratch. It seems like the "pure" way to do it. But it seems like everything has more stuff behind it. Making an h1 tag doesn't magically make a headline. There's code behind it. I don't know if "professional" developers use boilerplate. But I bet they have their ways of doing things. Seems pretty close to the same thing to me.