An interactive web app can be built to transcribe YouTube videos quickly using Streamlit, a Python library that simplifies web development. The app leverages Assembly AI's API to upload and transcribe audio files effortlessly. The process begins by setting up the project structure, installing necessary dependencies, and creating a base Streamlit app for testing purposes. This involves using three main libraries: Streamlit for developing the front-end interface, YouTube_dl for downloading YouTube videos, and FFmpeg for extracting audio from these videos.