If you’re familiar with This American Life, listen to the “Parent Trap” episode. It deals with a girl whose mom dies of cancer and has written letters to her to read after her death. It’s very insightful, particularly about some of the negative ramifications. It’ll give you some good perspective about what to focus on in your letters (or videos). Namely, in the midst of all the advice you want to give her, don’t forget to give her the freedom to ultimately be who she wants to be.