IndexError: list index out of range in PyCharm

You are most likely missing the arguments.

When you run,

python myscript.py arg1 arg2

sys.argv is a list with myscript.py at sys.argv[0],arg1 at sys.argv[1], etc

So consider using if conditions or try-except to check if we have necessary arguments to unpack:

import subprocess
import sys

if len(sys.argv)>2:

    myscript.pyvideo_link, threads = sys.argv[1], sys.argv[2]
    subprocess.call([
   "youtube-dl",
    video_link,
   "--external-downloader",
   "aria2c",
   "--external-downloader-args",
   "-x"+threads
])

else:
    print('Missing Video link and thread arguments')
    #raise Error if desired