Enhance video modal: increase size and add download functionality

index.html

@@ -251,6 +251,7 @@
                         <div id="video-progress-fill" class="video-progress-fill"></div>
                     </div>
                     <span id="video-time">0.0s</span>
+                    <button id="video-download-btn" onclick="downloadVideo()" style="background: var(--color-accent-success); margin-left: 0.5rem;">⬇ Download</button>
                 </div>
             </div>
         </div>