C# - How to update Youtube metadata

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO;
using System.Text.RegularExpressions;
using System.Threading;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Upload;
using Google.Apis.Util.Store;
using Google.Apis.YouTube.v3;
using Google.Apis.YouTube.v3.Data;
private async Task update_videos()
    String client_secret_path = ""; // here you put the path to your .json client secret file, generated in your Google Developer Account
    String username = ""; // youtube account login username
    UserCredential credential;
    using (var stream = new FileStream(client_secret_path, FileMode.Open, FileAccess.Read))
        credential = await GoogleWebAuthorizationBroker.AuthorizeAsync(
            new[] { YouTubeService.Scope.Youtube, YouTubeService.Scope.YoutubeUpload },
            new FileDataStore(this.GetType().ToString())
    var youtubeService = new YouTubeService(new BaseClientService.Initializer()
        HttpClientInitializer = credential,
        ApplicationName = this.GetType().ToString()
    // first, we get the video we want to update
    var my_video_request = youtubeService.Videos.List("snippet, status");
    my_video_request.Id = ""; // the Youtube video id of the video you want to update
    my_video_request.MaxResults = 1;
    var my_video_response = await my_video_request.ExecuteAsync();
    var video = my_video_response.Items[0];
    // then we change it's attributes
    string title = "New title";
    string description = "New description";
    List<String> keywords = new List<String>();
    video.Snippet.Title = title;
    video.Snippet.Description = description;
    video.Snippet.Tags = new System.Collections.Generic.List<String>();
    // and tell the changes we want to youtube
    var my_update_request = youtubeService.Videos.Update(video, "snippet, status");