Here's a common situation. A lot of times 5 year olds desperately want you to be with them, but then they want to do something that you find less than enthralling, like coloring, or building with legos, or whatever doesn't turn you on. Sometimes our typical kids only experience our bodies in the room, and our minds are somewhere else. Sometimes videos are a way of keeping a child occupied so you can get something else done. You praise, encourage, touch, instruct, a lot more than you probably do with your typical child.
Kids notice stuff like that.
Finally, your typical child is probably worried about his brother. He may not hear the words, but he sees your facial expressions, your posture. He needs reassurance that everything is okay right now, that his brother needs extra help, or medicine, or to go to the doctor to feel better, or the hospital to feel better. But not details about the medical problems. My thoughts here are not direct recommendations for any specific family, and are not intended as professional advice.