为什么我录制的视频经过改造上传到服务器后变成了0字节？

const express = require('express');
const multer = require('multer');
const fs = require('fs');

const app = express();
const upload = multer({ dest: 'uploads/' });

app.post('/upload', upload.single('video'), (req, res) => {
  if (!req.file) {
    return res.status(400).send('No file uploaded.');
  }

  const filePath = req.file.path;
  const newFilePath = `./uploads/${req.file.originalname}`;

  fs.rename(filePath, newFilePath, (err) => {
    if (err) {
      console.error(err);
      return res.status(500).send('Failed to save file.');
    }

    res.send('File uploaded successfully.');
  });
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});