diff --git a/vllm/multimodal/video.py b/vllm/multimodal/video.py
index 4a82dd24e75..c9751ecc66a 100644
--- a/vllm/multimodal/video.py
+++ b/vllm/multimodal/video.py
@@ -885,7 +885,6 @@ class GLM46VVideoBackend(VideoBackend):
         extract_t = min(extract_t, cls._MAX_FRAME_COUNT_DYNAMIC)
 
         duration_per_frame = 1 / original_fps if original_fps > 0 else 0
-        timestamps = [i * duration_per_frame for i in range(total_frames_num)]
         max_second = int(duration) if duration else 0
 
         if total_frames_num < extract_t:
@@ -897,7 +896,7 @@ class GLM46VVideoBackend(VideoBackend):
             current_second = 0.0
             inv_fps = 1 / (temporal_patch_size * target_fps)
             for frame_index in range(total_frames_num):
-                if timestamps[frame_index] >= current_second:
+                if frame_index * duration_per_frame >= current_second:
                     current_second += inv_fps
                     frame_indices.append(frame_index)
                     if current_second >= max_second:
@@ -991,7 +990,6 @@ class GLMGAVideoBackend(VideoBackend):
         extract_t = min(extract_t, max_frames)
 
         duration_per_frame = 1 / original_fps
-        timestamps = [i * duration_per_frame for i in range(total_frames_num)]
 
         if total_frames_num < extract_t:
             frame_indices = [
@@ -1002,7 +1000,7 @@ class GLMGAVideoBackend(VideoBackend):
             current_second = 0.0
             inv_fps = 1 / target_fps
             for frame_index in range(total_frames_num):
-                if timestamps[frame_index] >= current_second:
+                if frame_index * duration_per_frame >= current_second:
                     current_second += inv_fps
                     frame_indices.append(frame_index)
                     if current_second >= duration - inv_fps: