google youtube api v3 get playlist Items return no result

Question

I try to use this link to get the playlist item,
http://developers.google.com/youtube/v3/docs/playlistItems/list

There is a "try-it" interface in the bottom of the page, I input "contentDetails" or "snippet" in the "part", "PL4BF5198F14EEC8A5" in the "ID" field and push "execute". But the result has no item in.

If I use this link in the youtube, I can get the playlist.
http://www.youtube.com/playlist?list=PL4BF5198F14EEC8A5

So I want to ask if I fill anything wrong in the "try-it" table.

Answer 1

Make sure you're putting the playlist ID under the "playlistId" field further down the page and NOT the first "id" field.

Answer 2

You need to be authorized for that call to go through, did you click on the "Authorize requests using OAuth 2.0" switch to authorize the page to get that list on your behalf (using oAuth2)?