Websites offering video streaming often provide previews, like YouTube's hover thumbnails or frame slideshows, using techniques that can be implemented with Node.js and FFmpeg. FFmpeg is a versatile multimedia framework capable of handling various video manipulation tasks, accessible via the node-fluent-ffmpeg library, which simplifies command generation and execution. This approach allows developers to create video fragment previews by extracting sections from specific points in the video, typically between 25-75% of its length, and frame previews by capturing frames at regular intervals. Both methods involve calculating the video's duration with ffprobe and using Node.js functions to execute FFmpeg commands, ensuring efficient processing across different platforms. While the article provides Node.js code examples for generating these previews, it emphasizes using low-resolution outputs to optimize loading times on user devices. Additionally, the author highlights FFmpeg’s broad applicability, even demonstrating how to convert videos to GIFs efficiently, showcasing the tool's extensive utility for developers.