Upload a file to YouTube. Console application.

program.cs

using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Services;
using Google.Apis.Util.Store;
using Google.Apis.YouTube.v3;
using Google.Apis.YouTube.v3.Data;

namespace YouTubeExampleUpload
{
    class Program
    {
        public static readonly string PathToCredentials = @"C:\YouTube\dev\credentials.json";
        public static readonly string UploadFileName = "TestVideo.mkv";
        
        static async Task Main(string[] args)
        {
            Console.WriteLine("Hello World!");

            var userCredentials = await ConfigureUserCredential();
            var service = CreateService(userCredentials);

            var video = new Video
            {
                Snippet = new VideoSnippet
                {
                    Title = "Test video",
                    Description = "Upload dummy video"
                }
            };
            
            video.Status = new VideoStatus {PrivacyStatus = "unlisted"};

            var videoUploader = new UploadVideo(service);

            await videoUploader.Upload(video, UploadFileName);
        }

        private static async Task<UserCredential> ConfigureUserCredential()
        {
            // Credential storage location 
            var tokenStorage = new FileDataStore("UserCredentialStoragePath", true);

            UserCredential credential;
            await using var stream = new FileStream(PathToCredentials, FileMode.Open, FileAccess.Read);
            // Requesting Authentication or loading previously stored authentication for userName
            credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
                    (await GoogleClientSecrets.FromStreamAsync(stream)).Secrets,
                    new[] {YouTubeService.ScopeConstants.Youtube},
                    "userName",
                    CancellationToken.None,
                    tokenStorage)
                .Result;

            return credential;
        }

        private static YouTubeService CreateService(UserCredential credential)
        {
            return new YouTubeService(new BaseClientService.Initializer()
            {
                HttpClientInitializer = credential
            });
        }
    }

}

UploadVideo.cs

using System;
using System.IO;
using System.Threading.Tasks;
using Google.Apis.Upload;
using Google.Apis.YouTube.v3;
using Google.Apis.YouTube.v3.Data;

namespace YouTubeExampleUpload
{
    public class UploadVideo
    {
        private readonly YouTubeService _service;

        public UploadVideo(YouTubeService service)
        {
     
            _service = service;
        }
        
        public async Task Upload(Video video, string uploadFileName)
        {
            
            using (var fileStream = new FileStream(uploadFileName, FileMode.Open))
            {
                var videosInsertRequest = _service.Videos.Insert(video, "snippet,status", fileStream, "video/*");
                videosInsertRequest.ProgressChanged += videosInsertRequest_ProgressChanged;
                videosInsertRequest.ResponseReceived += videosInsertRequest_ResponseReceived;

                await videosInsertRequest.UploadAsync();
            }
        }
        

        public void videosInsertRequest_ProgressChanged(Google.Apis.Upload.IUploadProgress progress)
        {
            switch (progress.Status)
            {
                case UploadStatus.Uploading:
                    Console.WriteLine("{0} bytes sent.", progress.BytesSent);
                    break;

                case UploadStatus.Failed:
                    Console.WriteLine("An error prevented the upload from completing.\n{0}", progress.Exception);
                    break;
            }
        }

        public void videosInsertRequest_ResponseReceived(Video video)
        {
            Console.WriteLine("Video id '{0}' was successfully uploaded.", video.Id);
        }
    }
}