Misti, I asked this same question here to the pros at California Superbike School (CSS).
Pre-viewing a track - Cornering - Cornering Forum
I'm pretty new to the track scene, but I've done it every time before I go and i find it helps provide a certain degree of familiarity. If you can find the videos CSS made, they can be really helpful, because often times you can find the dots they place on the track before they start teaching. The dots represent a nominal turn point. I say nominal, because turn points are different for everyone, but it gives the students someplace to start from. So, its really a well-placed reference point.
Otherwise, I find the videos online to not allow you to see enough to make any super precise reference points of your own. Typically the wide-angle nature of the lens distorts the sides (places where your references are usually located) of the image too much.
Having said all that, I really like to watch a decent rider to try and pick up his/her line. Also, maybe you can see some brake marker boards that are useful.
I have a track day coming up and I have several copies of the track layout printed out. I plan to try and curb my enthusiasm enough to come up with a systematic way of identifying various reference points for each turn and documenting them at the end of each session. I'll try and record as much info as I can recall like shift points, gear, entry speed, etc. Not sure how much I will remember after a 20 min session, but that is the plan at least.
Anyone else have any strategies for learning/analyzing a track?