Thanks guys, I was coming up against this issue as well. That was a big help.

As Caro suggested, I used SEO Quake to check the results for a keyword where I could only see the top 9.
As expected, the 10th google result was a video. I looked at the stats and saw that the 11th result had a page rank of 3. This corresponds to a yellow value for the other results, meaning I should avoid this keyword; however elsewhere on this forum it has been explained that the colour of the SEO matrix fields reflects more than just the field value.

So I'm left wondering: am I analysing this correctly?