fix: Remove opacity from video widget

lib/pages/chat/events/message_content.dart

@@ -109,16 +109,13 @@ class MessageContent extends StatelessWidget {
               return Stack(
                 alignment: Alignment.center,
                 children: <Widget>[
-                  Opacity(
+                  ImageBubble(
-                    opacity: 0.4,
-                    child: ImageBubble(
                     event,
                     width: 400,
                     height: 300,
                     fit: BoxFit.cover,
                     tapToView: false,
                   ),
-                  ),
                   FloatingActionButton.extended(
                     onPressed: () => showDialog(
                       context: Matrix.of(context).navigatorContext,