//★ファイルを開くダイアログ処理
var targetFileText = "";
var targetPageName = "";
function openFileDialog(str,page){
	if(form_iframe.csvup.upload){
		targetFileText = str;
		targetPageName = page;
		form_iframe.csvup.upload.click();
	}
}
function setedFileName(str){
	var obj;
	var sendStr = "";

	obj = getElement(targetPageName);
	if(obj != null){
		//ここでFlashに表示したい場合はSetVariableなどでセットしてください。
		targetFileText = "";
		targetPageName = "";
	}
}
function fileUpload(str){
	if(form_iframe.csvup.upload.file != ""){
		form_iframe.csvup.action = str;
		form_iframe.csvup.CsvIn.click();
	}
}

<form name="csvup" method="post" enctype="multipart/form-data" action="" target="_parent">
	<input type="file" name="upload" onChange="parent.setedFileName(this.value)" />
	<input type="submit" name="CsvIn" />
</form>