Writing is cheap, portable, and available to anyone who can produce and process written script; the poorest child in the poorest country can be taught to write their ideas in a journal. Video is expensive: not just the personal device & storage account, but the entire infrastructure to support uploading, storing, and maintaining an always-accessible archive. It is also difficult to revisit video to search for previous ideas and thoughts, etc. Text is easy to index and search both in digital and analog formats (at least, if one gives forethought to indexing one's journals during or shortly after writing a journal entry).