diff --git a/src/lib/constants.ts b/src/lib/constants.ts
index 21f0ab870e..130722b9c5 100644
--- a/src/lib/constants.ts
+++ b/src/lib/constants.ts
@@ -181,6 +181,10 @@ export const VIDEO_SERVICE = 'https://video.bsky.app'
 export const VIDEO_SERVICE_DID = 'did:web:video.bsky.app'
 
 export const VIDEO_MAX_DURATION_MS = 3 * 60 * 1000 // 3 minutes in milliseconds
+/**
+ * Maximum size of a video in megabytes, _not_ mebibytes. Backend uses
+ * ISO megabytes.
+ */
 export const VIDEO_MAX_SIZE = 1000 * 1000 * 100 // 100mb
 
 export const SUPPORTED_MIME_TYPES = [