My custom upload field is not posting correctly

I am creating a field type that uploads a video file to Youtube upon post submission. I plan to use a file upload input type, and upon submission grab the file data (or url/pathname) and upload it to Youtube. This is part of a client project that I have to build in three weeks.

I've created a custom field by using the following hooks:

add_action("gform_field_input", array('GFYoutubeUpload', 'add_gf_fieldtype'), 10, 5);
add_filter("gform_editor_js_set_default_values", array('GFYoutubeUpload', 'add_gf_def
add_action("gform_editor_js", array('GFYoutubeUpload', 'add_gf_formeditor'));
add_filter("gform_field_type_title", array('GFYoutubeUpload', 'add_gf_title'));
add_filter("gform_add_field_buttons", array('GFYoutubeUpload', 'add_gf_button'));

(I also have a pre_submission handler that I've begun to write.)

I've created a File input type, and I believe that I have the correct naming convention. I've posted my function below for review.) The input type is displaying correctly on the admin page and the form preview, but when I post the form, my custom field doesn't have a value associated with it. (There's nothing in $_POST corresponding to it, either.)

Looking at the code below, can anybody tell me where I've gone wrong creating this input? Is there another hook that I don't know about that I need to use to handle the data I've added to the form?

/* Register the cusitom field type with Gravity Forms. */
    public static function add_gf_fieldtype($input, $field, $value, $lead_id, $form_id) {
        if ($field["type"] == "youtube") {
            $input_name = $form_id .'_'. $field['id'];
            $css = isset($field['cssClass']) ? $field['cssClass'] : '';

            return sprintf("<div class='ginput_container'><input name='input_%s' id='input_%s_%s' class='%s' value='' type='file' /></div>", $field["id"], $form_id, $field["id"], $field["type"]. ' ' .esc_attr($css). ' ' .$field['size']);
        }

        return $input;
    }

Thank you.

Thank you for your reply.

You were right - I was able to find the file in the $_FILES superglobal, and I'm now able to upload it to Youtube. I've run into another issue, though - my field entry isn't displaying in the Entries screen, even though I'm explicitly adding the Youtube URL to the $entry object in post submission. See the code below.

/* Pre-submission hook: grab the Youtube field values and send them
     * to the Youtube class. */
    public static function post_gf_youtubefields($form) {
        $yt_field_array = array();

        foreach($form["fields"] as $field) {
            if ($field["type"] == "youtube") {
                $yt_field_array[] = $field;
            }
        }

        foreach($yt_field_array as $field) {
            // Upload the file to Youtube.
            $yt_file =  $_FILES['input_'.$field['id']]['tmp_name'];
            echo $yt_file;
            $yt_video_url = GFYoutubeUpload::upload_to_youtube($yt_file);

            // Save the field ID and URL as a key-value pair for later use.
            self::$entry_ids[$field['id']] = $yt_video_url;

            if (file_exists($_FILES['input_'.$field['id']]['tmp_name'])) {
                unlink($yt_file);
            }
        }
    }

    /* Post-submission hook: write the Youtube URL to the now-available entry object. */
    public static function write_yt_url($entry, $form) {
        foreach (self::$entry_ids as $key => $value) {
            $entry[$key] = $value;
        }
    }

I've been looking into functions like gforms_entries_field_value and gform_entry_field_value, but it doesn't look as though I can grab anything. (In fact, I just poked around in the wp_rg_lead databases, and it doesn't look as though any value is grabbed.)

Because I'm using a file upload field, do I need to do an explicit write to the wp_rg_lead_detail database with my data? Or is the data stored/captured elsewhere?

Again, I appreciate all of the help.

Edit: If this would be better as a separate post, let me know.

I see. Is there a Gravity Forms API that I can use to write to that table, or will I have to use the wpdb class?