Insert hardware vids into csintro pages (#1828)

* Insert hardward vids into csintro pages

* bad paste of link

docs/courses/csintro/algorithms/activity.md

@@ -152,6 +152,14 @@ input.onButtonPressed(Button.B, () => {
 })
 ```
 
+### ~ hint
+
+Did you ever wonder how those LEDs turn on and make light? Well, watch this video and find out!
+
+https://www.youtube.com/watch?v=qqBmvHD5bCw
+
+### ~
+
 ## Test your program!
 Remember, MakeCode automatically compiles and runs your program, so all you need to do now is press button A and then button B in the simulator to see the output produced by your code. 
 

docs/courses/csintro/binary/activity.md

@@ -96,6 +96,14 @@ input.onButtonPressed(Button.AB, () => {
 })
 ```
 
+### ~ hint
+
+Buttons are on all kinds of electronic devices that we use. Did ever wonder how they actually work to signal an input event?
+
+https://www.youtube.com/watch?v=t_Qujjd_38o
+
+### ~
+
 Let’s work on what to do when button A is pressed. 
 * Button A represents a binary “1”. Our first task is to join a “1” to the existing string variable called binary.
 * From the Text Toolbox drawer (under the Advanced menu), drag the 'join' block to your programming workspace

docs/courses/csintro/booleans/project.md

@@ -179,7 +179,16 @@ This example uses boolean operations because both light level AND temperature mu
 ```block
 if (128 > input.lightLevel() && 0 < input.lightLevel() && input.temperature() > 22) {}
 ```
- 
+### ~ hint
+
+The @boardname@ uses some clever tricks to measure both light and temperature. Want to see how it can measure the light level and temprature? Watch these videos to learn how it does it.
+
+https://www.youtube.com/watch?v=TKhCr-dQMBY
+<br/>
+https://www.youtube.com/watch?v=_T4N8O9xsMA
+
+### ~
+
 ### Two-player game
 
 Create a game in which two players take turns on the same micro:bit. You can use a boolean variable called PlayerATurn to keep track of whose turn it is.

docs/courses/csintro/conditionals/project.md

@@ -67,6 +67,14 @@ input.onGesture(Gesture.Shake, () => {
 })
 ```
 
+### ~ hint
+
+The @boardname@ uses its accelerometer to detect when you're shaking it. How does an accelerometer actually work?
+
+https://www.youtube.com/watch?v=byngcwjO51U
+
+### ~
+
 ## Beta Testing
 
 Give students a chance to play each other’s games. The following process works well:

docs/courses/csintro/coordinates/activity.md

@@ -75,6 +75,14 @@ led.plot(2, 3)
 led.plot(3, 3)
 ```
 
+### ~ hint
+
+LEDs are amazing little devices. If you haven't seen this video about how they work, take a few minutes to learn more about them.
+
+https://www.youtube.com/watch?v=qqBmvHD5bCw
+
+### ~
+
 ## Mod this!
 * Add a third image to the animation, perhaps a frown face. 
 * Make your own custom animation! What LEDs stay the same and which need to be toggled?

docs/courses/csintro/variables/activity.md

@@ -200,6 +200,14 @@ PlayerBWins = 0
 PlayersTie = 0
 ```
 
+### ~ hint
+
+Buttons have been used as human input devices since computers first existed. Watch this video and see how they let tell the @boardname@ to do something.
+
+https://www.youtube.com/watch?v=t_Qujjd_38o
+
+### ~
+
 ## Try it out!
 Download the Scorekeeper program to the micro:bit, and have the students play one last round of Rock Paper Scissors using their micro:bits to act as the Scorekeeper!