diff --git a/multi_Thread/ledThreads/2020_08_14.md b/multi_Thread/ledThreads/2020_08_14.md
index a26aabbb099b3f7200969da5fb1e3a594aa4c3fe..e578997363b4fad360c77fd262a144af49ea53cf 100644
--- a/multi_Thread/ledThreads/2020_08_14.md
+++ b/multi_Thread/ledThreads/2020_08_14.md
@@ -97,19 +97,19 @@ Makefile이 생성된 후, make를 입력하여 응용 프로그램을 생성하
 ####  3-1) ./main
 
 
-<video src = "./0.mp4" controls>
-</video>
+<iframe width="560" height="315" src="https://www.youtube.com/embed/NfKf4ip-5uo" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
 <br><br>
 
 ####  3-2) ./main 1 5
 
-<video src = "1.mp4" controls>
-</video>
-####  3-2) ./main 2 7
+<iframe width="560" height="315" src="https://www.youtube.com/embed/UKGIucKDOBQ" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
+<br><br>
+
+####  3-3) ./main 2 7
+
+<iframe width="560" height="315" src="https://www.youtube.com/embed/5sroLUnva3o" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
+<br><br>
 
-<video src = "2.mp4" controls>
-</video>
-####  3-2) ./main 3 6
+####  3-4) ./main 3 6
 
-<video src = "3.mp4" controls>
-</video>
\ No newline at end of file
+<iframe width="560" height="315" src="https://www.youtube.com/embed/z_3D1bgHnQE" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
\ No newline at end of file