Fix readme videos (#51)

* docs: fix video links in readme

* docs: fix video preview sizing by switching out for gif

* docs: fix readme media layout

README.md

@@ -6,13 +6,11 @@ Input images and videos, describe the subjects or objects you want to keep, and
 
 **Check out the docs! [ezsam.org](https://www.ezsam.org)**
 
-<img src="examples/car-3.gui.png" height=200 />
-<video src="examples/food.mp4" height=200 controls>
-  A large table with plates of Thanksgiving food including a whole turkey on a conveyor-style lazy susan.
-</video>
-<video src="examples/food.turkey.webm" height=200 controls>
-  A whole cooked turkey flying through the void.
-</video>
+<p>
+  <img src="examples/car-3.gui.png" height=200 />
+  <img src="examples/food.gif" height=200 alt="A large table with plates of Thanksgiving food including a whole turkey on a conveyor-style lazy susan." />
+  <img src="examples/food.turkey.gif" height=200 alt="A whole cooked turkey flying through the void." />
+</p>
 
 <img src="examples/car-3.both.png" width=150 />