+ Added all my custom commands

.local/bin/custom/ff2mpv

@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+
+import sys
+import struct
+import json
+from subprocess import Popen, DEVNULL
+
+
+def main():
+    message = get_message()
+    url = message.get("url")
+    args = ["mpv", "--no-terminal", "--", url]
+    Popen(args, stdin=DEVNULL, stdout=DEVNULL, stderr=DEVNULL)
+    # Need to respond something to avoid "Error: An unexpected error occurred"
+    # in Browser Console.
+    send_message("ok")
+
+
+# https://developer.mozilla.org/en-US/Add-ons/WebExtensions/Native_messaging#App_side
+def get_message():
+    raw_length = sys.stdin.buffer.read(4)
+    if not raw_length:
+        return {}
+    length = struct.unpack("@I", raw_length)[0]
+    message = sys.stdin.buffer.read(length).decode("utf-8")
+    return json.loads(message)
+
+
+def send_message(message):
+    content = json.dumps(message).encode("utf-8")
+    length = struct.pack("@I", len(content))
+    sys.stdout.buffer.write(length)
+    sys.stdout.buffer.write(content)
+    sys.stdout.buffer.flush()
+
+
+if __name__ == "__main__":
+    main()