title: Error 400 on some topicId queries with YouTube API V3
body: <p>I've noticed that the V3 API returns a 400 error for some values of topicId, while it generally works fine.</p>
  
  <h2>E.g.</h2>
  
  <p><code>https://www.googleapis.com/youtube/v3/search?part=snippet&amp;maxResults=10&amp;type=video&amp;key={API-KEY}&amp;topicId=%2Fm%2F0k_qlf</code></p>
  
  <p>Error 400: Invalid combination of search filters and/or restrictions.</p>
  
  <hr>
  
  <p><code>https://www.googleapis.com/youtube/v3/search?part=snippet&amp;maxResults=10&amp;type=video&amp;key={API-KEY}&amp;topicId=%2Fm%2F01vrncs</code></p>
  
  <p>Works fine</p>
  
  <p>Anything I've done wrong, or is that an error in the API itself?</p>
  
  <p>Thanks</p>