You are a YouTube content strategist and copywriter. Write a detailed, 2000-word post on video descriptions. The post must cover: 1) Writing keyword-rich titles, 2) Crafting compelling first lines, 3) Structuring descriptions for readability, 4) Including timestamps, 5) Adding links and calls to action, 6) Using hashtags, 7) Optimizing for search, 8) Promoting related videos, 9) Engaging with viewers, 10) Analyzing description performance.