HttpPostFileBase in MVC3

ScreenshotControllerAsync.cs

[Authorize]
        [HttpPost]
        public void ScreenshotsAsync(string appName, HttpPostedFileBase files)
        {
            AsyncManager.OutstandingOperations.Increment();

            var fileModel = new UploadedFileModel();

            var result = UploadedFileResult.NoFile;

            var app = _appService.GetAppByWebFriendlyName(appName);

            try
            {
                if (AppService.IsAppInvalid(app))
                {
                    result = UploadedFileResult.NoApp;
                }
                else if (UserDoesntHavePermission(app))
                {
                    result = UploadedFileResult.NoPermissions;
                }
                else
                {
                    if (files == null || files.ContentLength == 0)
                    {
                        Trace.TraceWarning("Attempt to save screenshot contained no file.");

                        result = UploadedFileResult.NoFile;
                    }
                    else
                    {

                        //Valid the contents of the image...
                        var isFileValid = FileUploadValidator.FileIsWebFriendlyImage(files.InputStream, ByteCalculator.Megabytes(5));

                        if (isFileValid)
                        {
                            var fileName = files.FileName;
                            var imageId = Guid.NewGuid().ToString();
                            var thumbnail = ThumbnailHelper.GetResizedImage(files.InputStream);

                            var thumbnailUri = _storageService.UploadImage(User.Identity.Name,
                                                        string.Format("thumb-{0}-{1}", imageId, fileName),
                                                        files.ContentType, thumbnail);

                            var fullImageUri = _storageService.UploadImage(User.Identity.Name,
                                                        string.Format("{0}-{1}", imageId, fileName),
                                                        files.ContentType, files.InputStream);

                            var content =
                                XfstAppContent.Create(app.Owners.First(x => x.UserName.Equals(User.Identity.Name)),
                                                      AppContentType.Photo);

                            content.AppName = app.AppName;
                            content.ContentTitle = files.FileName;
                            content.ContentUrl = fullImageUri;
                            content.ThumbnailUrl = thumbnailUri;

                            var contentAddResult = _appService.AddAppContent(content);

                            if (contentAddResult.GetType() == typeof(MissingXfstAppContent))
                            {
                                result = UploadedFileResult.Failure;
                            }
                            else
                            {
                                fileModel = new UploadedFileModel
                                                {
                                                    delete_type = "DELETE",
                                                    delete_url =
                                                        GetDeleteUrl(
                                                            System.Web.HttpContext.Current,
                                                            contentAddResult.ContentId),
                                                    name = fileName,
                                                    size = files.ContentLength,
                                                    thumbnail_url = thumbnailUri,
                                                    url = fullImageUri
                                                };

                                result = UploadedFileResult.Success;
                            }

                        }
                        else
                        {
                            result = UploadedFileResult.InvalidFileType;
                        }

                    }
                }
            }
            catch (Exception ex)
            {
                Trace.TraceError("Error trying to save file to storage. Exception: {0}, Trace: {1}", ex.Message, ex.StackTrace);
                result = UploadedFileResult.Failure;
            }

            AsyncManager.Sync(() =>
            {
                AsyncManager.Parameters["file"] = fileModel;
                AsyncManager.Parameters["result"] = result;
                AsyncManager.OutstandingOperations.Decrement();
            });

        }

Screenshotvew.CSHTML

 <div id="fileupload">
                @using (Html.BeginForm("Screenshots", "Uploads", new { appName = Model.WebFriendlyName }, FormMethod.Post, new { enctype = "multipart/form-data", id = "file_upload" }))
                {
                    <div class="fileupload-buttonbar">
                        <input type="hidden" name="protocol" value="http" />
                        <label class="fileinput-button">
                            <span>Add files...</span>
                            <input type="file" name="files" id="filetargets" multiple />
                        </label>
                        <button type="submit" class="start">
                            Start upload</button>
                        <button type="reset" class="cancel">
                            Cancel upload</button>
                        <button type="button" class="delete">
                            Delete files</button>
                    </div>
                }
                <div class="fileupload-content">
                    <table class="files">
                    </table>
                    <div class="fileupload-progressbar">
                    </div>
                </div>
            </div>


<script src="@Url.Content("~/Scripts/jquery.fileupload.js")" type="text/javascript" language="javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.fileupload-ui.js")" type="text/javascript" language="javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.iframe-transport.js")" type="text/javascript" language="javascript"></script>
<script type="text/javascript" language="javascript">

    /*global $ */
    $(function () {

        // Initialize the jQuery File Upload widget:
        $('#fileupload').fileupload({
            url: '@Url.Action("Screenshots", "Uploads", new { appName = Model.WebFriendlyName })',
            type: 'POST',
            dataType: 'json',
            fileInput: $('#filetargets'),
            uploadTemplate: $('#template-upload'),
            downloadTemplate: $('#template-download'),
            acceptFileTypes: /\.(gif|jpe?g|png)$/i,
            maxFileSize: 5000000,
            maxNumberOfFiles: 20,
            autoUpload: false
        });

        // Open download dialogs via iframes,
        // to prevent aborting current uploads:
        $('#fileupload .files a:not([target^=_blank])').live('click', function (e) {
            e.preventDefault();
            $('<iframe style="display:none;"></iframe>')
            .prop('src', this.href)
            .appendTo('body');
        });

    });

</script>