#!/bin/bash

a='
{
 "kind": "yt#playlistItemListResponse",
 "etag": "\"hvjhjjvhj_hvhv/jvjhvjhvj-dd\"",
 "nextPageToken": "CDIQAA",
 "pageInfo": {
	"totalResults": 199,
	"resultsPerPage": 50
 },
 "items": [
 ...
'
echo "$a" | grep nextPageToken | cut -d '"' -f4