gistfile1.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import json
import requests

url = "http://api.impossible.io/v1/token/upload/0fa84b7d-51b034861-9a7d-501a9b289e08.mp4"

payload = {
    "task": {
        "destination":  {
            "type": "facebook",
            "description": "Adèle",
            "oauth_access_token": "CAACEdEose0cBAAZCzSAC1MeUZCOk1hZA1m0t6DlcIjD28lSFZBue9uj28ckvKk6sYFFmYSfR3zQeOZC8q2KA8DVemp9d1BCdiKktUijMNyohzCYZAD72cyvUsueZBYwlHHrjZCMasrZB5sOlD4ruaPVtJfESDDeuQZBETJI8r6tYQWKjpqacoXOs9WfNd0TZArUmF6d7HeYbIwO57TwqrkVHUDH"
        }
    }
}

r = requests.post(url, data=json.dumps(payload), headers={'content-type': 'application/json'})

print(r.text)