To allow URLs I had to modify https://github.com/ArsalanDotMe/VideoStitch/blob/master/lib/videoconcat.js#L48
let child = shelljs.exec(`ffmpeg -f concat -i ${args.fileList} -c copy ${outputFileName}`, { async: true, silent: spec.silent });
to
let child = shelljs.exec(`ffmpeg -f concat -safe 0 -protocol_whitelist file,http,https,tcp,tls -i ${args.fileList} -c copy ${outputFileName}`, { async: true, silent: spec.silent });