Since Google has deprecated the YouTube v2 API, I cannot find a way to get all the comments from a video.
Is it possible to use a single, non-deprecated API (Google+, YT v3) to do that?
I am not concerned about maintaining threading.
Believe me it works and I am 100 % sure
https://www.googleapis.com/youtube/v3/commentThreads?key=******************&textFormat=plainText&part=snippet&videoId=kffacxfA7G4&maxResults=50
Key will be provided by the google developer console and 50 denotes 50 comments in form of a json. for any type of queries comment below and video id id of the video
Apparently it is now possible to fetch comment threads.
(old answer)
Currently that's impossible with a first-party tool.
Source:
While v3 offers the majority of v2 functionality, there are currently a couple of tasks that can only be done with the older API. Specifically, applications that manage captions or that work with video comments still need to use the v2 API until modern equivalents are available. Our goal is to provide similar functionality well before the April 2015 shut-off date—please subscribe to this blog, the YouTube Data API v3 revision history page, or follow +YouTubeDev on Google+ to keep up-to-date. - http://apiblog.youtube.com/2014/03/committing-to-youtube-data-api-v3.html
TubeKit (YouTube crawling toolkit) might be of help to some.
You can get only 100 at most at a time with the comments API. But you get a nextPageToken from the comment api response. Pass &pageToken={nextPageToken} to next api call, until the nextPageToken is undefined. Then you can get all comments if you like.
https://www.googleapis.com/youtube/v3/commentThreads?key={your_api_key}&textFormat=plainText&part=snippet&videoId={video_id}&maxResults=100&pageToken={nextPageToken}
$.ajax({
dataType: "jsonp",
type: 'GET',
url: "https://www.googleapis.com/youtube/v3/commentThreads?key=PUT-YOUR-KEYXXXXXXX&textFormat=plainText&part=snippet&videoId=PUT-YOUR-VIDEO-ID",
success: function(result){
data = result;
$('.data').text(data);
console.log(data);
}});
To find PUT-YOUR-KEY(API key) ---> https://console.developers.google.com/apis/credentials then click on blue color button select API key option you can get
来源：https://stackoverflow.com/questions/19965856/how-to-get-all-comments-on-a-youtube-video