I use Mr. Andersen's videos all the time in my AP Biology class as a precursor to my lectures. This is my write-a-long, or WAL as I call them, for his "Water Potential" video.
My WAL is broken into the sections shown within the video (intro/vocabulary, equations, sample problems) and is mainly fill-in-the-blank/work with Mr. Andersen as the video plays. At the end of the video, I include another water potential problem for students to solve (the problem/answer are not in the video) and discuss the next day.
Please note that there is no key included with this product. It's good for you to watch the video so you know what your students will see, anyway :)