Fix issue of using only the part of video frame [Nemotron Nano] (#26186)

Signed-off-by: Eugene Khvedchenia <ekhvedchenia@nvidia.com>

vllm/model_executor/models/nano_nemotron_vl.py

@@ -208,7 +208,7 @@ def video_to_pixel_values(
         )
         # dynamic_preprocess returns tensors already; take the single tile
         assert len(pil_frame) >= 1
-        frames_tensors.append(pil_frame[0])
+        frames_tensors.append(pil_frame[-1])
 
     return torch.stack(frames_tensors)