I would augment A to "the rate at which you read while learning is highly variable throughout the material and differs from person to person". Sometimes I can plow through a chapter in an 20 minutes and sometimes it takes me a week to get one paragraph. And the paragraph that takes me a week you might get in 5 minutes. With text we can each go at our own pace and trivially change pace with the nature of the material. With video we all get the same pace and it's the pace the instructor thinks is best.