Odnoklassniki Downloader extension (IDL Helper) is the most advanced extension. After using it, I realized that this extension gives me many special advantages over others, namely:
It is very easy to use and anyone can use it.
You can choose the format and resolution of the video as you like, which is very difficult to do otherwise.
Video resolution is widely available.
Loading speed is better than any video which loads very fast.
In addition, this software has many more advantages that cannot be explained without using it. I think everyone should use it. Highly recommend!