Loopline uses @ffmpeg/ffmpeg 0.12.15 (MIT).
Source: https://github.com/ffmpegwasm/ffmpeg.wasm
License: ./vendor/ffmpeg/LICENSE

The conversion engine @ffmpeg/core 0.12.10 is fetched from jsDelivr only when conversion is required.
It contains FFmpeg and supporting codec libraries, with their respective licenses, including GPL components.
Core source and build instructions: https://github.com/ffmpegwasm/ffmpeg.wasm
FFmpeg source: https://ffmpeg.org/download.html
FFmpeg license information: https://ffmpeg.org/legal.html
ffmpeg.wasm licensing: https://ffmpegwasm.netlify.app/docs/faq/

YouTube videos are played through the official YouTube IFrame Player API.
No YouTube videos are downloaded or converted by this app.