Fix 2 minor "bugs"

Change empty string comparison to string.isNullOrEmpty and move video format check before empty time parameter check

Commands/Modules/VideoUtils.cs

@@ -27,17 +27,17 @@ public async Task TrimVideoAsync(
 		// Achknowledge the command
 		await DeferAsync(ephemeral);
 
-		// There is a similar check for the TimeSpan library below, but this it to avoid 
-		if (trimStartString == "" && trimEndString == "")
+		// Reject incorrect video formats
+		if (video.ContentType != "video/mp4")
 		{
-			await FollowupAsync("You must provide a start or end time to trim the video.", ephemeral: true);
+			await FollowupAsync("Invalid video format. Please provide an MP4 file.", ephemeral: true);
 			return;
 		}
 
-		// Reject incorrect video formats
-		if (video.ContentType != "video/mp4")
+		// There is a similar check for the TimeSpan library below, but this it to avoid 
+		if (string.IsNullOrEmpty(trimStartString) && string.IsNullOrEmpty(trimEndString))
 		{
-			await FollowupAsync("Invalid video format. Please provide an MP4 file.", ephemeral: true);
+			await FollowupAsync("You must provide a start or end time to trim the video.", ephemeral: true);
 			return;
 		}
 
@@ -171,4 +171,4 @@ public static TimeSpan TimeSpanFromHMS(string input)
 		// Create and return the TimeSpan object
 		return new TimeSpan(days: 0, hours, minutes, seconds, milliseconds);
 	}
-}
+}