Engineering a High-Performance Reddit Video Downloader: Decoding DASH, HLS, and Client-Side Transmuxing

As developers, we often perceive video downloading as a simple GET request to a .mp4 URL. However, modern social media giants like Reddit have moved far beyond static file hosting. Today, Reddit employs sophisticated Adaptive Bitrate Streaming (ABS) to optimize bandwidth and user experience. In this article, I will break down the technical journey of building Reddit Video Downloader, exploring how we bypassed protocol limitations, handled asynchronous stream merging, and leveraged WebAssembly to