I have a bit of experience in this area. I live in a developing country and house cancer patients in my home. When they are terminal and the hospital cannot help anymore I help them get back to their families (often 1000+ miles away) or offer them a comfortable place to die and bring families to them (resources permitting). The biggest thing that I've found that these families need is to know and be known by their dying father/mother/etc. before the end. The "life advice" is a nice part of that but when I can encourage and facilitate a father opening up to his son or daughter about his past, his failures, his thoughts, his pain, his love, his adventures, his first kiss, his best friends in grade-school, his favorite games of soccer in school, how he met his wife (the child's mother), and any number of other stories... THESE things are what the grown child treasures. OP: I would advise making individual videos that each tell a story from your past. Talk about times you were disappointed. Talk about the humbling secrets that others cannot tell because no one else knew the story but you. If you list off your achievements it means little. Your wife and family members know those. Tell her about when you first learned about science and what joys it brought. Tell her how you felt when you started educating others and the way your heart flipped when you met your wife. Tell her how your almost dropped her when she was born because you were so emotional. Tell her that you knew so little about being a father that you put the diaper on wrong the first few times. Tell her about watching her grow and how frustrating and hard it was to be self-sacrificial for those years and how much it took out of you to do that. Tell her that she was worth so much more than the years you've been given to be self-sacrificial.
These stories and emotions will, I believe, be treasured far more than encouragement to pursue understanding differential equations, elliptic curve encryption, chemical biology, Linux kernel contributions, or any number of geeky things.
Well done for caring about how you leave your family. That is rare and you are to be commended for it. I like to tell my patients that they are not running out of time. They are running into eternity. You don't have to drag your feet in this. There will be tremendous pain and there will be devastating days and nights as your body weakens. You are running into eternity OP. I hope you run your race well.