Link to embeddings explainer video (#768)

Author: Paul-Cornell

ui/embedding.mdx

@@ -2,6 +2,16 @@
 title: Embedding
 ---
 
+<iframe
+  width="560"
+  height="315"
+  src="https://www.youtube.com/embed/CYSviKxwjuI"
+  title="YouTube video player"
+  frameborder="0"
+  allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture"
+  allowfullscreen
+></iframe>
+
 After partitioning, chunking, and summarizing, the _embedding_ step creates arrays of numbers 
 known as _vectors_, representing the text that is extracted by Unstructured. 
 These vectors are stored or _embedded_ next to the text itself. These vector embeddings are generated by an