When I started, I had real trouble picking up anything that was going on when watching a technique. I'm more of a tactile/kinesthetic learner vs. visual, so it wasn't until I felt the technique or got my own body moved around in the right position that I could approximate the external pieces.
So knowing that my visual side wasn't too capable initially, I would just try to watch one part, and rotate which part that was each time. So I would look at just the feet, and then when the technique was shown again, I would look at just the hands, etc.
Like you said, you'll be able to compare and contrast things soon enough. You'll start seeing common movements across different techniques, and eventually techniques that you've never seen before will be mostly made up of things you've done before.
But you might want to try and figure out what kind of learning you are. This is a highly unscientific but maybe useful starting point if you are interested in this sort of thing:
Might help you recognize whether you pick up more about a technique from watching it, hearing an explanation, or feeling it, and let you aim for the way that gives you the most bang for the buck.