I have searched in YouTube Documents and found nothing to get others channel name from a YouTube video.
That is,
I currently would like to get the channel name from a video, I only have the URL, how to get the channel name?
You can do this easily by using YouTube Data API v3.
The latest part in the URL after "http://www.youtube.com/watch?v=" is your VIDEO_ID.
Just do a videos->list with setting part="snippet". Then you can grab snippet.channelId in the response.
Request would be:
GET https://www.googleapis.com/youtube/v3/videos?part=snippet&id=EhNWzcUqGbI&key={YOUR_API_KEY}
for your example.
You can always try these using API explorer.
Great sample codes to get you started.