動画クリックでモーダルで再生されるようにするjs

```html
<!DOCTYPE html>
<html lang="ja">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>動画モーダル</title>
    <style>
        body { font-family: Arial, sans-serif; }
        .modal {
            visibility: hidden;
            opacity: 0;
            position: fixed;
            z-index: 1000;
            left: 0;
            top: 0;
            width: 100%;
            height: 100%;
            background-color: rgba(0, 0, 0, 0.8);
            justify-content: center;
            align-items: center;
            display: flex;
            transition: opacity 0.3s ease-in-out;
        }
        .modal.active {
            visibility: visible;
            opacity: 1;
        }
        .modal-content {
            position: relative;
            width: 80%;
            max-width: 800px;
        }
        .modal video {
            width: 100%;
            display: block;
        }
        .close-btn {
            position: absolute;
            top: 10px;
            right: 10px;
            background: #fff;
            border: none;
            font-size: 18px;
            cursor: pointer;
            padding: 5px 10px;
            border-radius: 5px;
        }
        .play-btn {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            background: rgba(0, 0, 0, 0.6);
            color: white;
            font-size: 24px;
            border: none;
            cursor: pointer;
            padding: 10px 20px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        body.no-scroll {
            overflow: hidden;
        }
    </style>
</head>
<body>
    <!-- 自動再生動画（サムネイル） -->
    <video class="thumbnail" data-modal="videoModal" autoplay muted loop width="300">
        <source src="sample.mp4" type="video/mp4">
        お使いのブラウザは動画タグをサポートしていません。
    </video>
    
    <!-- モーダル -->
    <div class="modal" data-modal="videoModal">
        <div class="modal-content">
            <button class="close-btn">×</button>
            <video>
                <source src="" type="video/mp4">
            </video>
            <button class="play-btn">▶</button>
        </div>
    </div>

    <script>
        // サムネイル動画をクリックしたらモーダルを開く
        document.querySelectorAll(".thumbnail").forEach(video => {
            video.addEventListener("click", () => {
                const modal = document.querySelector(`.modal[data-modal='${video.dataset.modal}']`);
                const modalVideo = modal.querySelector("video");
                
                // 動画のソースを直接設定
                modalVideo.src = video.querySelector("source").src;
                modalVideo.load();
                
                modal.classList.add("active");
                document.body.classList.add("no-scroll");
            });
        });

        // モーダルの操作
        document.querySelectorAll(".modal").forEach(modal => {
            const closeButton = modal.querySelector(".close-btn");
            const playButton = modal.querySelector(".play-btn");
            const modalVideo = modal.querySelector("video");
            
            // モーダルを閉じる
            closeButton.addEventListener("click", () => {
                modal.classList.remove("active");
                modalVideo.pause();
                modalVideo.currentTime = 0;
                document.body.classList.remove("no-scroll");
            });
            
            // 再生・停止切り替え
            const togglePlay = () => {
                if (modalVideo.paused) {
                    modalVideo.play();
                    playButton.style.display = "none";
                } else {
                    modalVideo.pause();
                    playButton.style.display = "flex";
                }
            };
            
            playButton.addEventListener("click", togglePlay);
            modalVideo.addEventListener("click", togglePlay);
        });
    </script>
</body>
</html>

```