diff --git a/docs/src/configuration/source.md b/docs/src/configuration/source.md
index 0a3ed1dbc..80ba3ce61 100644
--- a/docs/src/configuration/source.md
+++ b/docs/src/configuration/source.md
@@ -232,6 +232,18 @@ headers:
   X-Custom-Auth: "my-secret-token"
 ```
 
+> **Note:** Some Flussonic providers select the catch-up format by `User-Agent`. With a VLC User-Agent (for example
+> `VLC/3.0.21 LibVLC/3.0.21`), they return separate fMP4 video and audio renditions whose initialization objects
+> (`.hls.fmp4`) fail with `403 Forbidden`, while the playlists still return `200`. The ffmpeg default User-Agent
+> (`Lavf/…`) receives a combined MPEG-TS rendition that plays. If catch-up stops at the fMP4 initialization
+> object, set a non-VLC `User-Agent` for this input. Then check that live and VOD playback still work, because
+> some providers require a specific User-Agent.
+>
+> A per-channel `#EXTVLCOPT:http-user-agent` directive in the provider playlist overrides the input `User-Agent`
+> on catch-up HLS requests. If a channel sets this directive to a VLC User-Agent, the input header has no effect
+> for that channel. Change the directive to a non-VLC User-Agent as well, for example in a local copy of the
+> playlist.
+
 ---
 
 ### 2.2 Input Options (`options`)
diff --git a/frontend/src/app/components/source_editor/editor_view.rs b/frontend/src/app/components/source_editor/editor_view.rs
index a10f61148..3e9810864 100644
--- a/frontend/src/app/components/source_editor/editor_view.rs
+++ b/frontend/src/app/components/source_editor/editor_view.rs
@@ -1763,7 +1763,10 @@ pub fn SourceEditor(props: &SourceEditorProps) -> Html {
                     }
                 }
 
-                if let Some(move_it) = compute_drag_move_params(&editor_state_ref.borrow(), mouse_x, mouse_y) {
+                // Bind first: an if-let scrutinee temporary would keep the borrow alive
+                // across move_blocks.emit, which needs borrow_mut.
+                let move_params = compute_drag_move_params(&editor_state_ref.borrow(), mouse_x, mouse_y);
+                if let Some(move_it) = move_params {
                     move_blocks.emit(move_it);
                     // Drag updates are applied directly to DOM for smoothness.
                     // Avoid full re-render on every mouse move while dragging blocks.
@@ -1891,7 +1894,8 @@ pub fn SourceEditor(props: &SourceEditorProps) -> Html {
                         let touch_x = client_x - rect.left() as f32;
                         let touch_y = client_y - rect.top() as f32;
 
-                        if let Some(move_it) = compute_drag_move_params(&editor_state_ref.borrow(), touch_x, touch_y) {
+                        let move_params = compute_drag_move_params(&editor_state_ref.borrow(), touch_x, touch_y);
+                        if let Some(move_it) = move_params {
                             move_blocks.emit(move_it);
                         } else {
                             force_update.set(*force_update + 1);