Update labels videos list on replace (#128)

sleap_io/model/labels.py

@@ -473,6 +473,13 @@ def replace_videos(
             video_map: Alternative input of dictionary where keys are the old videos and
                 values are the new videos.
         """
+        if (
+            old_videos is None
+            and new_videos is not None
+            and len(new_videos) == len(self.videos)
+        ):
+            old_videos = self.videos
+
         if video_map is None:
             video_map = {o: n for o, n in zip(old_videos, new_videos)}
 
@@ -486,6 +493,9 @@ def replace_videos(
             if sf.video in video_map:
                 sf.video = video_map[sf.video]
 
+        # Update the list of videos.
+        self.videos = [video_map.get(video, video) for video in self.videos]
+
     def replace_filenames(
         self,
         new_filenames: list[str | Path] | None = None,

tests/model/test_labels.py

@@ -356,16 +356,16 @@ def test_labels_remove_predictions(slp_real_data):
 def test_replace_videos(slp_real_data):
     labels = load_slp(slp_real_data)
     assert labels.video.filename == "tests/data/videos/centered_pair_low_quality.mp4"
-    labels.replace_videos(
-        old_videos=[labels.video], new_videos=[Video.from_filename("fake.mp4")]
-    )
+    labels.replace_videos(new_videos=[Video.from_filename("fake.mp4")])
 
     for lf in labels:
         assert lf.video.filename == "fake.mp4"
 
     for sf in labels.suggestions:
         assert sf.video.filename == "fake.mp4"
 
+    assert labels.video.filename == "fake.mp4"
+
 
 def test_replace_filenames():
     labels = Labels(videos=[Video.from_filename("a.mp4"), Video.from_filename("b.mp4")])