OO-2454 avoid npe if video has no metadata

src/main/java/org/olat/modules/video/manager/VideoMetadataDAO.java

@@ -66,7 +66,7 @@ public class VideoMetadataDAO {
 		if (metadata.size() > 0) {
 			return metadata.get(0);
 		} else {
-			return null;
+			return new VideoMetaImpl(800, 600, 5000);
 		}
 	}
 	

src/main/java/org/olat/modules/video/model/VideoMetaImpl.java

@@ -91,7 +91,12 @@ public class VideoMetaImpl implements VideoMeta, Persistable, ModifiedInfo {
 		this.length = length;
 	}
 	
-
+	public VideoMetaImpl(int width, int height, long size) {
+		this.width = width;
+		this.height = height;
+		this.size = size;
+	}	
+	
 	public VideoMetaImpl() {
 		// make JAXB happy
 	}