Question

I’m fairly new to using WebRequests in C# and would like some help logging into YouTube and storing cookies into a cookie container. Any help would be much appreciated.

Answer 1

If you are using the .NET client library (http://code.google.com/p/google-gdata/) then it will take care of authenticating for you when needed using the credentials you provided:

https://developers.google.com/youtube/2.0/developers_guide_dotnet#Authentication

GData in C#

When using the GData API there’s no explicit logout method, you can invalidate your token but it will also expire after some time if you don’t use it. Specific details on how to invalidate the token differ according to the authentication mechanism adopted (OAuth, AuthSub, ClientLogin).

You can also refer to this article on CodeProject, Manage YouTube using C# and Youtube API 1.6

YouTubeService service = new YouTubeService();
service.setUserCredentials(txtUser.Text , txtPassword.Text);
try { service.QueryClientLoginToken(); }
catch(System.Net.WebException e) { MessageBox.Show(e.Message); }

ADDED: I have tweaked below code to match your requirement.

class YouTube
{
    public void Login()
    {
        HttpWebRequest request = GetNewRequest("https://accounts.google.com/ServiceLoginAuth", cookies);
        request.Referer = "https://accounts.google.com/ServiceLogin?passive=true&continue=https%3A%2F%2Fwww.youtube.com%2Fsignin%3Faction_handle_signin%3Dtrue%26feature%3Dsign_in_button%26nomobiletemp%3D1%26hl%3Den_US%26next%3D%252F&uilel=3&hl=en_US&service=youtube";
        request.Host = "accounts.google.com";
        Dictionary<string, string> parameters = new Dictionary<string, string>{
            {"continue","https%3A%2F%2Fwww.youtube.com%2Fsignin%3Faction_handle_signin%3Dtrue%26feature%3Dsign_in_button%26nomobiletemp%3D1%26hl%3Den_US%26next%3D%252F"},
            {"service","youtube"},{"uilel","3"},{"dsh","157212168103955870"},{"hl","en_US"},
            {"GALX","PTqcwpZb2aE"},{"pstMsg","1"},{"dnConn",""}, {"checkConnection","youtube%3A248%3A1"}, 
            {"checkedDomains","youtube"}, {"timeStmp",""}, {"secTok",""}, {"Email","username"}, {"Passwd","password"}, 
            {"signIn","Sign+in"}, {"PersistentCookie","yes"}, {"rmShown","1"}};
        HttpWebResponse response = MakeRequest(request, cookies, parameters);
        response.Close();
    }

    private static CookieContainer cookies = new CookieContainer();

    private static HttpWebRequest GetNewRequest(string targetUrl, CookieContainer SessionCookieContainer)
    {
        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(targetUrl);
        request.CookieContainer = SessionCookieContainer;
        request.AllowAutoRedirect = false;
        return request;
    }

    private static HttpWebResponse MakeRequest(HttpWebRequest request, CookieContainer SessionCookieContainer, Dictionary<string, string> parameters = null)
    {
        request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.5 (KHTML, like Gecko) Chrome/19.0.1084.52 Safari/536.5Accept: */*";
        request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
        request.CookieContainer = SessionCookieContainer;
        request.AllowAutoRedirect = false;

        request.Method = "POST";
        request.ContentType = "application/x-www-form-urlencoded";
        string postData = string.Empty;
        foreach (KeyValuePair<String, String> parametro in parameters)
        {
            if (postData.Length == 0)                
                postData += String.Format("{0}={1}", parametro.Key, parametro.Value);                
            else                
                postData += String.Format("&{0}={1}", parametro.Key, parametro.Value);                
        }

        byte[] postBuffer = UTF8Encoding.UTF8.GetBytes(postData);
        using (Stream postStream = request.GetRequestStream())
        {
            postStream.Write(postBuffer, 0, postBuffer.Length);
        }

        HttpWebResponse response = request.GetResponse() as HttpWebResponse;
        SessionCookieContainer.Add(response.Cookies);

        while (response.StatusCode == HttpStatusCode.Found)
        {
            response.Close();
            request = GetNewRequest(response.Headers["Location"], SessionCookieContainer);
            response = (HttpWebResponse)request.GetResponse();
            SessionCookieContainer.Add(response.Cookies);
        }
        return response;
    }
}

Reference: http://social.msdn.microsoft.com/Forums/pl-PL/ncl/thread/40d249b5-a9ad-4068-8853-629fb20584a0