Error - System.Collections.Generic.List`1[System.String]

Hi

   When i am trying to get Tags i am getting above error.

using (var yt = new YouTubeService(new BaseClientService.Initializer()
{
    ApiKey = "MyApiKey",
}))
{
    StringBuilder htmlTable = new StringBuilder();

    var request = yt.Videos.List("snippet");
    request.Chart = VideosResource.ListRequest.ChartEnum.MostPopular;
    var response = request.Execute();
    var objResult = response.Items.ToList();
    if (objResult != null)
    {
        htmlTable.Append("");
        htmlTable.Append("");
        htmlTable.Append("");
        foreach (var colum in objResult)
        {
            htmlTable.Append("");

            htmlTable.Append("");
            htmlTable.Append("");
            htmlTable.Append("");
            htmlTable.Append("");
            htmlTable.Append("");
            htmlTable.Append("");
            htmlTable.Append("");

            htmlTable.Append("");
        }
        htmlTable.Append("");
        htmlTable.Append("
Category Id
Channel Id
Channel Title
Video Title
Description
Tags
Published
" + colum.Snippet.CategoryId + "
" + colum.Snippet.ChannelId + "
" + colum.Snippet.ChannelTitle + "
" + colum.Snippet.Title + "
" + colum.Snippet.Description + "
" + colum.Snippet.Tags + "
" + colum.Snippet.PublishedAt + "
");
        PlaceHolderTable.Controls.Add(new Literal { Text = htmlTable.ToString() });
    }
}

Thanks