Add more vids to 'Behind MakeCode HW' (#1994)

docs/behind-the-makecode-hardware.md

@@ -47,6 +47,18 @@
         "description": "Your board can communticate by radio, how does it do that?",
         "youTubeId": "Re3H2ISfQE8",
         "imageUrl": "/static/mb/behindhardware/radio.jpg"
+    },
+    {
+        "name": "Servo Motor",
+        "description": "See how motors work and how you can use the @boardname@ to run servos.",
+        "youTubeId": "okxooamdAP4",
+        "imageUrl": "/static/mb/behindhardware/servo.jpg"
+    },
+    {
+        "name": "Speakers",
+        "description": "Find out how speakers make sound and how you can connect them to your board.",
+        "youTubeId": "cxfPNc4Wefo", 
+        "imageUrl": "/static/mb/behindhardware/speakers.jpg"
     }
 ]
 ```