import requests
import json
link_pageToken = 'https://www.googleapis.com/youtube/v3/commentThreads?part=snippet&maxResults=100&pageToken={pageToken}&videoId={videoId}&key={key}'
key = API_KEY
videoId = '5ioa36WJmn0'
comments = []
link = 'https://www.googleapis.com/youtube/v3/commentThreads?part=snippet&maxResults=100&videoId={videoId}&key={key}'
r = requests.get(link.format(videoId=videoId, key=key))
data = r.json()
while 'nextPageToken' in data:
    link_pageToken = link + "&pageToken={pageToken}"
    r = requests.get(link_pageToken.format(videoId=videoId, key=key, pageToken=data['nextPageToken']))
    data = r.json()
    for i in range(len(data['items'])):
        comments.append(data['items'][i]['snippet']['topLevelComment']['snippet']['textOriginal'])