[Stream] clarifying (#21710)

Author: tsmith512

src/content/docs/stream/pricing.mdx

@@ -7,8 +7,8 @@ sidebar:
 
 Cloudflare Stream lets you broadcast, store, and deliver video using a simple, unified API and simple pricing. Stream bills on two dimensions only:
 
-- Minutes of video stored
-- Minutes of video delivered
+- **Minutes of video stored:** the total duration of uploaded video and live recordings
+- **Minutes of video delivered:** the total duration of video delivered to end users
 
 On-demand and live video are billed the same way.