diff --git a/strawApp/src/main/kotlin/com/sulkta/straw/net/IosSafeHttpDataSource.kt b/strawApp/src/main/kotlin/com/sulkta/straw/net/IosSafeHttpDataSource.kt
index 4e9eb7583..ffb92672f 100644
--- a/strawApp/src/main/kotlin/com/sulkta/straw/net/IosSafeHttpDataSource.kt
+++ b/strawApp/src/main/kotlin/com/sulkta/straw/net/IosSafeHttpDataSource.kt
@@ -162,6 +162,12 @@ class IosSafeHttpDataSource(
     }
 
     companion object {
-        const val DEFAULT_CHUNK_BYTES: Long = 1L * 1024 * 1024
+        // YT's iOS-bound googlevideo URLs accept bounded `Range: bytes=N-M`
+        // requests up to roughly 900 KiB before flipping to 403. Empirically
+        // measured 2026-05-24 on Lucy egress: bytes=0-917503 (~896 KiB) → 206;
+        // bytes=0-999999 (~977 KiB) → 403. 512 KiB gives a 2× safety margin —
+        // small enough to survive future tightening, large enough to keep the
+        // open() round-trip count tolerable for a long video.
+        const val DEFAULT_CHUNK_BYTES: Long = 512L * 1024
     }
 }