Download a portion of a youtube using yt-dlp and ffmpeg - requires Python 3, yt-dlp and ffmpeg (all must be on the path)

yt-dl.py

import argparse
import subprocess
import sys

def create_parser():
    p = argparse.ArgumentParser()
    p.add_argument('url', help='youtube URL', nargs='?')
    p.add_argument('-ss', '--seek', help='position in time to start at', default='00:00:00')
    p.add_argument('-t', '--time', help='time of clip/duration', default='00:00:01')
    p.add_argument('-o', '--output', help='output file name', default='output.mp4')
    p.add_argument(
        '-p', '--path', 
        help='full or relative path for source and destination', 
        default='/mnt/c/Users/apkat/Videos'
    )
    return p

if __name__ == '__main__':
    parser = create_parser()
    args = parser.parse_args()
    
    if not args.url:
         parser.print_help()
         sys.exit(0)

    # Setup command for youtube-dl 
    yt_dl_cmd = ['yt-dlp', '--youtube-skip-dash-manifest', '-g', args.url]
    # Run youtube-dl command
    result = subprocess.run(yt_dl_cmd, stdout=subprocess.PIPE, universal_newlines=True)
    # Split resultant URLs on new lines
    urls = result.stdout.splitlines()

    if len(urls) > 1 and urls[1] != '':
        # FFmpeg options for mapping audio and video
        ff_options = '-map 0:v -map 1:a -c:v libx264 -c:a aac'
        # Assemble full command
        ff_cmd = 'ffmpeg -y -ss {} -i "{}" -ss {} -i "{}" -t {} {} {}/{}'.format(
            args.seek, urls[0], args.seek, urls[1], args.time, ff_options, args.path, args.output)
    else:
        ff_options = '-c:v libx264 -c:a aac'
        ff_cmd = 'ffmpeg -y -ss {} -t {} -i {} {} {}/{}'.format(
            args.seek, args.time, urls[0], ff_options, args.path, args.output)

    # Run FFmpeg command
    subprocess.call(ff_cmd, shell=True)

Usage looks like python3 yt-dl.py "https://www.youtube.com/watch?v=1234" -ss 00:16:06 -t 00:00:04 -o test.mp4