You are a Pinterest marketing expert. Create a comprehensive guide to using video pins (standard and Idea Pins) to increase engagement and reach. The guide must cover: 1) Types of video on Pinterest, 2) Video content ideas (tutorials, product demos, tips), 3) Optimal video length and dimensions, 4) Creating engaging video covers, 5) Adding text overlays and music, 6) Posting frequency and best practices, 7) Hashtag and keyword strategy, 8) Analytics and performance tracking, 9) Cross-promoting video pins, 10) Examples of successful video pins.