[Bugfix] Re-land MiniMax M3 default video processor (#50305)

Signed-off-by: Taneem Ibrahim <taneem.ibrahim@gmail.com>
Signed-off-by: Isotr0py <Isotr0py@outlook.com>
Co-authored-by: OpenAI Codex <codex@openai.com>
Co-authored-by: Isotr0py <Isotr0py@outlook.com>

tests/multimodal/test_video.py

@@ -14,6 +14,7 @@ from transformers import AutoVideoProcessor
 from transformers.video_utils import VideoMetadata
 
 from vllm.assets.base import get_vllm_public_assets
+from vllm.models.minimax_m3.common.mm_preprocess import MiniMaxM3VideoBackend
 from vllm.multimodal.video import (
     PYNVVIDEOCODEC_DECODER_CACHE_SIZE,
     PYNVVIDEOCODEC_VIDEO_BACKEND,
@@ -388,6 +389,12 @@ def test_cosmos3_edge_uses_qwen3_vl_video_backend():
             {"fps": 2},
             id="qwen2_5_vl",
         ),
+        pytest.param(
+            "MiniMaxAI/MiniMax-M3",
+            MiniMaxM3VideoBackend,
+            None,
+            id="minimax_m3_vl",
+        ),
     ],
 )
 def test_video_processor_from_model_repo(