SEO mistakes in this video?

I've watched this video and used some code to build my website.
Now I was wondering if there's anything here that's incorrect regarding SEO and was wondering if anyone will give an opinion of it.

YouTube Video

Layout/style of a website generally doesn't have a major impact on SEO. There's a few minor things to keep in mind. For example, title tags, headings, and URLs help inform search engines what you're page is about, so make sure to use those appropriately. For the most part, what is covered in "intro to web design" type videos doesn't have much to do with SEO either way.

Disclaimer: I didn't actually watch that hour long video