docs: use youtube embed instead of local video (#35)

* docs: upload demo.mp4 without lfs to fix website

* docs: use youtube embed instead of local video

Author: CodeF0x

.gitattributes

@@ -51,7 +51,7 @@
       background-color: #333;
     }
 
-    video {
+    iframe {
       max-width: 40%;
       max-height: 40%;
       border: 1px solid #333;
@@ -100,10 +100,7 @@
     </div>
     <p>A blazing fast & convenient CLI for batch media processing using FFmpeg with parallel execution.</p>
 
-    <video controls loop muted>
-      <source src="demo.mp4" type="video/mp4">
-      Your browser does not support the video tag.
-    </video>
+    <iframe src="https://www.youtube.com/embed/Hx1t5qFPO2Q" allowfullscreen></iframe>
 
     <div class="buttons">
       <a href="#examples" class="button">Examples</a>