Still I feel IDM is faster because it can split a file up to 16 parts and uses the all the bandwidth it can get to hasten the download.IDM can still download videos from other video sharing site and MP3s as well with no problem so I think this problem is only confined to YouTube. It can download pretty much all files you can think of, has a decent User Interface, and it also have a file-splitting-synchronous-download feature with up to 4 segmentations. The problem is it doesn't have the multi-file-splitting-synchronous download capability (whatever that's called) that IDM has (it took me 30 mins to download a file that can usually be downloaded with IDM in less than 5 minutes).The best solution I come with is a program called Download Accelerator Plus. I tried downloading the videos with YouTube Downloader (there's a lot of program to choose from anyway) and the videos played perfectly with all the media players I have installed in my computer and with sounds. You can download the accompanying MPA and listen to the audio separately but the point is its really inconvenient. You can download the MP4 and it would play on Windows Media Player Classic and WMP11 however you won't hear any audio for there really is no audio stream embedded in the file. The download panel would only list MP4 and MPA download options. It only happens when you try to download YouTube videos with Internet Download Manager(IDM). I first had this problem when I started using VPN to access YouTube. I've updated all the codecs on the system in my hope to resolve it but to no avail.

Convert youtube video to mp4 vlc