So I am trying to learn how to from this [video](https://www.youtube.com/watch?v=lwb-ubQdsKU). I have very limited know-how to read basic note symbols. This is my first time trying to read a Piano sheet.

For left hand only: At 0:02 (first measure), the author pressed the D key. I thought it should be B. Again at 0:05 (2nd measure) the author pressed a B flat instead of a G flat. Again at 0:09 (third measure) The author pressed a G instead of an E. Etc. It looked like the author brought those notes 3 half steps up. When I played like as it has shown on the sheet, it did not sound right. But I played like her finger then it sounded better.

So, is reading left hand Piano sheet portion not the same as normal note reading?