that is a great site. But I have found one or two fonts that are not actually free for commercial purposes. It must have been something they overlooked. That is why is always to not only check the license text provided there but also look for the original site of the author and read the license there.
I have found the same problem. I have a couple of unique fonts from fontsquirrel and I’m not sure I can use those on templates. I guess that the fonts that are just for preview are not ok for templates.