What if YouTube owner doesn't respond if I can use their upload further?
Nothing, really. YouTube Standard License doesn't give you any rights to redistribute or remix the video (see my answer here). You can only try to contact the uploader through other means. Look through their channel info to see if you can find a website, Twitter, E-Mail address or any other contact information. Depending on how badly you want to use this video, there are also other means of online stalking finding contact information that you might try. For example, if he uses a distinct user name you can try to search for that user name on Google, Twitter or other social media and see if you find something.