diff --git a/library/build.gradle b/library/build.gradle
index 6ba2e1ad6d..45b6e69fe5 100644
--- a/library/build.gradle
+++ b/library/build.gradle
@@ -19,6 +19,11 @@ android {
     buildToolsVersion "21.1.2"
 
     defaultConfig {
+        // Important: ExoPlayerLib specifies a minSdkVersion of 9 because
+        // various components provided by the library may be of use on older
+        // devices. However, please note that the core video playback
+        // functionality provided by the library requires API level 16 or
+        // greater.
         minSdkVersion 9
         targetSdkVersion 21
     }