感谢你的关注，提前祝你春节愉快^_^
下面是我学写的代码，如果有时间麻烦替我看下，先谢谢了。
File ：UploadfilesForm.php

...
class UploadfilesForm extends Model
{

public $videoFile;
public $videoName;
public $videoCategory;
public $videoCover;

public function rules(){
    return [
        [['videoFile'],'file', 'extensions'=>['jpg','mp4','rmvb']],
        [['videoName'],'required'],
        //[['videoCategory'],'required'],
        //[['videoCover'],'file','extensions'=>['jpg','png','gif']]
    ];
}//rules()

public function upload(){

        $strUrl = '/video/' . $this->videoFile->baseName . '.' . $this->videoFile->extension;

    if($this->validate()){
        $this->videoFile->saveAs($strUrl);
        return TRUE;
    }
    else{
        return FALSE;
    }
}//upload()

}//class UploadfilesForm extends Model

File : UploadfilesController.php
...
class UploadfilesController extends Controller
{

public function actionUpload(){
    //$enableCsrfValidation = FALSE;
    $model = new UploadfilesForm();
    
    if(Yii::$app->request->isPost){
        $model->videoFile = UploadedFile::getInstance($model, 'videoFile');
        if($model->upload()){
            echo '文件上传成功'; 
            return exit('文件上传成功');
        }
    }//if(Yii::$app->request->isPost)
    return $this->render('uploadvideos',['model'=>$model]);
}//public function actionUpload()

}//class UploadfilesController extends Controller

File : uploadvideos.php
<?php
use yii\widgets\ActiveForm;

?>

<?php $form = ActiveForm::begin(['options' => ['enctype' => 'multipart/form-data']]) ?>

<?php echo $form->field($model, 'videoName')->textInput()->hint('请输入电影名称（不是文件名），不要包含扩展名。')->label('电影名称：'); ?>
<?php //echo $form->field($model, 'videoCategory')->dropDownList(['dzp'=>'动作片','jqp'=>'剧情片','znl'=>'正能量'], ['prompt'=>'请选择','style'=>'width:120px'])->label('请选择影视类型'); ?>




<?php echo $form->field($model, 'videoFile')->fileInput()->hint('请注意：仅支持扩展名为 mp4 的影视文件。')->label('影视文件：'); ?>
<?php //echo $form->field($model, 'videoCover')->fileInput()->hint('请选择海报文件。')->label('影视海报：'); ?>

<button>上传影视</button>

<?php ActiveForm::end() ?>

<p><hr></p>

public function rules() {
    //parent::rules();
    return [
        [['keyword'],'match','pattern'=>'~\s+~','message'=>'请不要输入空格']
    ];
}