Ok, maybe. Let me try to translate the abstract. I hope you and others can confirm my translation.
They mutation rate was estimated by using other studies that have rates at specific loci (positions in the genes) and other studies that looked directly at new (because they weren't causing illness in the parents I presume -- the point of the "dominant" in the note) mutations that are seen because they cause disease.
From these they arrive at an estimate of the mutation rate.
A reason why this might be taken as meaningful is because the independent result matches with the 'historic' extrapolation in the differences between us and chimps.
The results also show that there is agreement (I don't know the stats well enough to say how well it agrees) between different loci.
The rest discusses the kinds of mutations and how they are related.
The fact that the simpler mutations (and less likely to result in a non-viable) organisms are far more common also supports the conclusion.
I don't know the significance of: "Rates of different kinds of mutations are strongly correlated across loci."