This video was uploaded in August 2011, well before Penguin update. It addresses keyword density issues and in my opinion explains keyword stuffing very clearly. There is no doubt about importance of keywords. You still need to use them to ensure that search engines can pick up the subject of your article or post, but you don’t need to repeat it over and over again in order to rank. Not even 1 percent! You just need to be natural and this video explains what is meant by natural really well.
The problem is that many of us are so used to idea that you have to repeat a keyword a certain number of times that some can’t even see what’s wrong with this practice. They sincerely don’t understand why would it be suddenly considered manipulative and bitterly resent Google for running Penguin algorithm. But in reality these are no new rules. Google didn’t suddenly change the rules, they merely implemented an algorithm that ranks sites that ignore their rules lower – something they always promised. Basically, the rules were always there, so it’s hard to blame them. To be honest these changes make me only happy, because now I can build great sites without worrying much about keywords.