removing videos from docs

docs/lessons/counter/challenges.md

@@ -16,8 +16,6 @@ input.onButtonPressed(Button.A, () => {
 
 ### Challenge 1
 
-### @video td/videos/counter-1-2
-
 Let's add the code to `count` when `B` is pressed. Add an event handler with `on button pressed(B)` then add the code to `count`.
 
 
@@ -33,7 +31,6 @@ input.onButtonPressed(Button.B, () => {
 })
 ```
 
-
 ### Challenge 3
 
 Now let's try to reset the counter when the micro:bit is shaken. You will need to register an event handler with `on shake`.