download youtube with idm and no sound

Hi, I just download from youtube and the mp4 file I played with media classic player but there is no sound. Someone can halp me?
Answer #1
Try Re downloading it and also check the original video for sound …………..
Answer #2
I search from google
http://malaysia.answers.yahoo.com/question/index?qid=20130414031313AA8KDDH
someone give an answer
That's not your computer's problem, it's Youtube. For some reason, they separate audio and video into separate files. Maybe so that people couldn't download videos from their site, who knows?
Try searching for a video player that can change it's audio track. You know, play the video first, then use the .M4A file as the audio track.
GOM and VLC doesn't support this function.
Answer #3
If IDM is anything like JDownloader, when you copy a URL from Youtube to download it’ll give you different files and different formats, if you’re choosing MP4 see if there’s an M4A link as well. If not, use either a different format and convert to MP4 afterwards or use a better tool (JDownloader) or a site like deturl (add pwn to the front of the address) eg:
http://www.pwnyoutube.com/watch?v=Elczv0ghqw0&feature=youtu.be
Answer #4
Never heard about this problem. You sure you have all the codec properly installed? Try a different player and also try downloading a different format of the file.
Answer #5
I got this problem too on another PC and changing the version of Firefox to an older one solved the issue.
Answer #6
Whats the url?