async function downloadVideo(videoUrl) {
    const downloadBtn = document.querySelector('#downloadBtn'); // 替换为你页面中下载按钮的 selector
    if (downloadBtn) downloadBtn.innerText = '正在下载中...';

    try {
        // 前端直接请求视频文件
        const response = await fetch(videoUrl);
        const blob = await response.blob();
        
        // 创建本地 Blob URL 触发真正下载
        const blobUrl = URL.createObjectURL(blob);
        const a = document.createElement('a');
        a.href = blobUrl;
        a.download = `video_${Date.now()}.mp4`;
        document.body.appendChild(a);
        a.click();
        document.body.removeChild(a);
        URL.revokeObjectURL(blobUrl);

        if (downloadBtn) downloadBtn.innerText = '下载无水印视频';
    } catch (error) {
        // 如果跨域阻拦，降级方案：在新窗口直接打开视频，提示用户右键另存为
        window.open(videoUrl, '_blank');
        if (downloadBtn) downloadBtn.innerText = '下载无水印视频';
    }
}