Yeah, NeXTSTEP is notoriously a locked-down, untweakable OS. It's not like anyone was able to use it to program anything of consequence.
for wmv in Path(sys.argv[1]).rglob("\*.wmv"):
print(wmv, end=" ")
r = subprocess.run(
["ffmpeg", "-i", wmv, wmv.with_suffix(".mpg")],
stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
)
lines = [l for l in r.stdout.decode().splitlines() if "kb/s:" in l]
print("\n".join(lines) if lines else f"ERROR {r.returncode}")