Improve thumbnail loading reliability across the platform

Update video cards and video page to use a backup thumbnail URL from Bunny.net when the primary URL fails, enhancing robustness for video content display.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: d7424866-83d1-4486-a212-ac12b4c7becf
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/8cc42625-c1f5-4e43-99bd-77f2c4dedee2/d7424866-83d1-4486-a212-ac12b4c7becf/d3pjSXi

client/src/pages/VideoPage.tsx

@@ -244,7 +244,17 @@ export default function VideoPage() {
                       className="w-full h-full object-cover"
                       onError={(e) => {
                         const target = e.target as HTMLImageElement;
-                        target.style.display = 'none';
+                        // Try backup thumbnail URL
+                        const backupUrl = `https://iframe.mediadelivery.net/embed/476412/${video.id}/thumbnail.jpg`;
+                        if (!target.src.includes('iframe.mediadelivery.net')) {
+                          target.src = backupUrl;
+                        } else {
+                          target.style.display = 'none';
+                          if (target.parentElement) {
+                            target.parentElement.style.background = 'linear-gradient(45deg, #374151, #4b5563)';
+                            target.parentElement.innerHTML += '<div class="absolute inset-0 flex items-center justify-center text-white text-xs">Video</div>';
+                          }
+                        }
                       }}
                     />
                     <div className="absolute bottom-1 right-1 bg-black/70 text-white text-xs px-1 py-0.5 rounded">