Update constants.py

constants.py

@@ -243,9 +243,17 @@ LEADERBORAD_INTRODUCTION = """# VBench Leaderboard
     
     **Join Leaderboard**: Please see the [instructions](https://github.com/Vchitect/VBench/tree/master?tab=readme-ov-file#trophy-leaderboard) for 3 options to participate. One option is to follow [VBench Usage info](https://github.com/Vchitect/VBench?tab=readme-ov-file#usage), and upload the generated `result.json` file here. After clicking the `Submit here!` button, click the `Refresh` button.
 
-    **Get VBench Certified: Gold & Platinum Tiers**： 
-    - 🏅 Gold Certification: Awarded when you submit high-quality, pre-generated video samples from your model.
-    - 💎 Platinum Certification: Our highest honor. Achieved by submitting your open-source model or a sampling-capable API for full verification by our team.
+    **Get VBench Certified: Gold & Silver & Bronze Tiers**： 
+    We encourage developers of closed-source models to provide API access to us for evaluation via VBench.
+    Models are certified under VBench based on the transparency and rigor of the evaluation process:
+
+    🥇 Gold – Sampled and evaluated by the VBench team
+
+    🥈 Silver – Sampled by a partner team, evaluated by the VBench team
+
+    🥉 Bronze – Sampled by the model’s own team, evaluated by the VBench team
+
+    This certification helps ensure fair, consistent, and reproducible comparisons across models — making it easier for the community to track progress and identify strengths and weaknesses.
     
     **Ready to participate?**: Contact the VBench Team at ZIQI002@e.ntu.edu.sg to submit your work and earn your certification.