Font-Extractor.py

import subprocess
import sys
import re

var = str(subprocess.check_output(["mkvmerge.exe", "--identify", "video.mkv"]).decode(sys.stdout.encoding))

AttachmentID = re.findall(r"(Attachment ID (\d{1,2}):)", var)
AttachmentName = re.findall(r"(file name ('(.*)'))", var)

for a, b in zip(AttachmentID, AttachmentName):
    funnymanjoe = subprocess.Popen(["mkvextract.exe", "video.mkv", "attachments", a[1] + ":" + b[2]])
    print(a[1] + b[1])

Add python script to same directory as mkvtoolnix executables (or have them on path) and the video file named "video.mkv"

If on linux remove ".exe" from executable files