use video url as preview if duration <=2min

src/api.rs

@@ -1287,6 +1287,18 @@ async fn videos_post(
             .await;
     });
     //###
+
+    for video in videos.items.iter_mut() {
+        if video.duration <= 120 {
+            let mut preview_url = video.url.clone();
+            if let Some(x) = &video.formats {
+                // preview is a String here, so use it directly
+                preview_url = x[0].url.clone();
+            }
+            video.preview = Some(preview_url);
+        }
+    }
+
     Ok(web::HttpResponse::Ok().json(&videos))
 }