Fix hardcoded aliases

Author: nul800sebastiaan

src/Umbraco.Tests/Services/MediaServiceTests.cs

@@ -165,7 +165,7 @@ public void Cannot_Save_Media_With_Empty_Name()
             var mediaService = ServiceContext.MediaService;
             var mediaType = MockedContentTypes.CreateNewMediaType();
             ServiceContext.MediaTypeService.Save(mediaType);
-            var media = mediaService.CreateMedia(string.Empty, -1, "video");
+            var media = mediaService.CreateMedia(string.Empty, -1, Constants.Conventions.MediaTypes.VideoAlias);
 
             // Act & Assert
             Assert.Throws<ArgumentException>(() => mediaService.Save(media));
@@ -177,7 +177,7 @@ public void Ensure_Content_Xml_Created()
             var mediaService = ServiceContext.MediaService;
             var mediaType = MockedContentTypes.CreateNewMediaType();
             ServiceContext.MediaTypeService.Save(mediaType);
-            var media = mediaService.CreateMedia("Test", -1, "video");
+            var media = mediaService.CreateMedia("Test", -1, Constants.Conventions.MediaTypes.VideoAlias);
 
             mediaService.Save(media);