change vid to webm

src/blog/2023-08-23.md

@@ -54,7 +54,7 @@ tiny independent animations are everywhere on youtube - often made with so much
 [some outrageously smooth animations by birdman](https://skeb.jp/@birdman46049238)  
 <a href="https://skeb.jp/@birdman46049238/works/17">
     <video autoplay loop muted style="max-width: 75%;">  
-        <source src="/_assets/img/blog/birdman.mp4"></source>  
+        <source src="/_assets/img/blog/birdman.webm"></source>  
     </video>  
 </a>