diff --git a/multi_Thread/ledThreads/0.mp4 b/multi_Thread/ledThreads/0.mp4
deleted file mode 100644
index a2f0b7f5cffabb5991ad53a762e46d617ca05f43..0000000000000000000000000000000000000000
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diff --git a/multi_Thread/ledThreads/1.mp4 b/multi_Thread/ledThreads/1.mp4
deleted file mode 100644
index 9aa9465d1568c0ff6a8e7f2b6a23401212612e2c..0000000000000000000000000000000000000000
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diff --git a/multi_Thread/ledThreads/2.mp4 b/multi_Thread/ledThreads/2.mp4
deleted file mode 100644
index 9bf1d1a35e57c0502457ed0b82939178ed3e6710..0000000000000000000000000000000000000000
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diff --git a/multi_Thread/ledThreads/2020_08_14.md b/multi_Thread/ledThreads/2020_08_14.md
index 43b90a60caab027cffdbd416214a441d7d78dbca..037bdbb52b8959dddd58face041ab54949401b99 100644
--- a/multi_Thread/ledThreads/2020_08_14.md
+++ b/multi_Thread/ledThreads/2020_08_14.md
@@ -96,27 +96,18 @@ Makefile이 생성된 후, make를 입력하여 응용 프로그램을 생성하
 
 ####  3-1) ./main
 
-<video>
-<source src = "0.mp4" type = "video/mp4">
-</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>
-<source src = "1.mp4" type = "video/mp4">
-</video>
-<br><br>
+<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>
 
 ####  3-2) ./main 2 7
 
-<video>
-<source src = "2.mp4" type = "video/mp4">
-</video>
-<br><br>
+<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>
 
 ####  3-2) ./main 3 6
 
-<video>
-<source src = "3.mp4" type = "video/mp4">
-</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
diff --git a/multi_Thread/ledThreads/3.mp4 b/multi_Thread/ledThreads/3.mp4
deleted file mode 100644
index 9bec26ea5940d2bdc8ab61057225f8b924d9977b..0000000000000000000000000000000000000000
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