Here are some videos discussing field sobriety tests. First, a great one that talks mostly about the Horizontal Gaze Nystagmus test:
Next, this one's just funny:
There's plenty of other good videos on field sobriety tests on YouTube, Google Video, and some other websites.
In my experience, police officers never do these correctly. They rarely understand the concept of nystagmus, for example, and how to apply it in the test of "maximum deviation" versus "angle of onset." They often misunderstand how to score the FSTs as well. And you tend to see a variety of other mistakes.