title: YouTube API without user OAuth process
body: <p>I am trying to fetch captions from YouTube video using YouTube Data API (v3)
  <a href="https://developers.google.com/youtube/v3/guides/implementation/captions" rel="noreferrer">https://developers.google.com/youtube/v3/guides/implementation/captions</a></p>
  
  <p>So, first I tried to retrieve a captions list using this url:
  <a href="https://www.googleapis.com/youtube/v3/captions?part=snippet&amp;videoId=KK9bwTlAvgo&amp;key=" rel="noreferrer">https://www.googleapis.com/youtube/v3/captions?part=snippet&amp;videoId=KK9bwTlAvgo&amp;key=</a>{My API KEY}</p>
  
  <p>I could retrieve the caption id that I'd like to download (jEDP-pmNCIqoB8QGlXWQf4Rh3faalD_l) from the above link.</p>
  
  <p>Then, I followed this instruction to download the caption: 
  <a href="https://developers.google.com/youtube/v3/docs/captions/download" rel="noreferrer">https://developers.google.com/youtube/v3/docs/captions/download</a></p>
  
  <p>However, even though I input the caption id and my api key correctly, it shows "Login Required" error. </p>
  
  <p>I suppose I need OAuth authentication, but what I am trying to do is not related to my users's account, but simply downloading public caption data automatically. </p>
  
  <p>My question is: Is there any way to process OAuth authentication just once to get an access token of my own YouTube account and then reuse it whenever I need it in my application?</p>