update zh-cn/application-dev/media/video-recorder.md.

Signed-off-by: Nzengyawen <zengyawen1@huawei.com>

zh-cn/application-dev/media/video-recorder.md

@@ -27,7 +27,7 @@ import media from '@ohos.multimedia.media'
 import mediaLibrary from '@ohos.multimedia.mediaLibrary'
 export class VideoRecorderDemo {
   private testFdNumber; // 用于保存fd地址
-  // pathName是传入的录制文件名，例如：01.mp3，生成后的文件地址：/storage/media/100/local/files/Video/01.mp4
+  // pathName是传入的录制文件名，例如：01.mp4，生成后的文件地址：/storage/media/100/local/files/Video/01.mp4
   // 使用mediaLibrary需要添加以下权限, ohos.permission.MEDIA_LOCATION、ohos.permission.WRITE_MEDIA、ohos.permission.READ_MEDIA
   async getFd(pathName) {
     let displayName = pathName;