title: why this thread doesnt run parelally?
body: <p>Hi I have the following code:</p>
  <pre><code>def record_video(task_id):    
  
      (
          ffmpeg
          .input('a.mp4', t=t)
          .output(f'{task_id}.mp4')
          .run()
      )
  
  
  thread = Thread(target=record_video, args=(f'{uuid.uuid1()}.mp4'))
  
  thread.start()
  
  print('end job')
  </code></pre>
  <p>The idea is that <code>print('end job')</code> runs first, but anyway this waits until record_video thread ends, how can I solve this?</p>
  <p>Thanks</p>