GoogleCloudVideoIntelligenceSandbox.ConsoleApp.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.0</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Google.Cloud.VideoIntelligence.V1Beta1" Version="1.0.0-alpha03" />
  </ItemGroup>

</Project>

Program.cs

using System;
using System.Linq;
using System.Threading.Tasks;
using Google.Cloud.VideoIntelligence.V1Beta1;

namespace GoogleCloudVideoIntelligenceSandbox.ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            MainAsync().GetAwaiter().GetResult();
        }

        static async Task AnalizeLablesAsync(string inputUri, string outputUri)
        {
            AnnotateVideoRequest request = new AnnotateVideoRequest()
            {
                Features = { Feature.LabelDetection },
                InputUri = inputUri,
                OutputUri = outputUri,
                LocationId = @"asia-east1",
            };

            var videoClient = VideoIntelligenceServiceClient.Create();
            var operation = await videoClient.AnnotateVideoAsync(request);
            var resultOperation = await operation.PollUntilCompletedAsync();
            var result = resultOperation.Result.AnnotationResults.First();

            foreach (var label in result.LabelAnnotations)
            {
                Console.WriteLine($"Label description: {label.Description}");
                Console.WriteLine($"Locations:");

                foreach (var item in label.Locations.Select((location, index) => new { location = location, index = index }))
                {
                    Console.WriteLine($"\t{item.index}: {item.location.Segment.StartTimeOffset} to {item.location.Segment.EndTimeOffset}");
                }
            }
        }

        static async Task MainAsync()
        {
            var inputVideoUri = $"gs://yourInputVideoFile.avi";
            var outputResultJson = $"gs://yourOutputResultJson.json";

            await AnalizeLablesAsync(inputVideoUri, outputResultJson);
            Console.ReadKey();
        }
    }
}