Youtube: 403 Forbidden errors

Hi, 

Using 3.2.9, and the following code

```c#
var youtube = YouTube.Default;
var vid = youtube
  .GetAllVideos("https://www.youtube.com/watch?v=NRvTj2zM5Uw")
  ?.OrderByDescending(s => s.AudioBitrate)
  .FirstOrDefault();
var x = vid.GetBytes();
``` 


This gives the following error on the GetBytes()

> Response status code does not indicate success: 403 (Forbidden).

