Youtube Data API C# - use without requesting user credentials

If you want to retrieve information (title, thumbnail) of a public playlist, you only need an API key. You only need to authenticate the user if you want to create or edit playlists.

This sample program retrieves the title and the thumbnail of a playlist by id.

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Google.Apis.Services;
using Google.Apis.YouTube.v3;

namespace YtbExample
{
    internal class PlayList
    {
        [STAThread]
        static void Main(string[] args)
        {
            try
            {
                new PlayList().Run().Wait();
            }
            catch (AggregateException ex)
            {
                foreach (var e in ex.InnerExceptions)
                {
                    Console.WriteLine("Error: " + e.Message);
                }
            }

            Console.WriteLine("Press any key to continue...");
            Console.ReadKey();
        }

        private async Task Run()
        {
            var youtubeService = new YouTubeService(new BaseClientService.Initializer()
            {
                ApiKey = "YOUR_API_KEY",
                ApplicationName = this.GetType().ToString()
            });

            var listRequest = youtubeService.Playlists.List("snippet");
            listRequest.Id = "PLdo4fOcmZ0oXzJ3FC-ApBes-0klFN9kr9";
            //Get playlists by channel id
            //listRequest.ChannelId = "";

            listRequest.MaxResults = 50;


            var listResponse = await listRequest.ExecuteAsync();

            List<string> playlists = new List<string>();

            // Add each result to the list, and then display the lists of
            // matching playlists.
            foreach (var result in listResponse.Items)
            {
                playlists.Add(String.Format("Title: {0}, Id: {1}, Thumbnail: {2}", result.Snippet.Title, result.Id, result.Snippet.Thumbnails.Medium.Url));
            }

            Console.WriteLine(String.Format("{0}\n", string.Join("\n", playlists)));
        }
    }
}

I hope I could help you!