[sagher]

right . with internet download manager it is very simple to download video not only for youtube but for other site too not only that but funny enough IT CAN BE USED TO DOWNLOAD GOOGLE TRANSLATE VOICE . i accendientaly found it while opening google translate and i can download the voice that generated by google translate

but i dont have time for installing idm and for downloading i use torrent most of the time . i rarely using direct download for huge file

You can try first to check your flash player version. is it updated? if yes and still got problem then check your flashplayer is IE compatible or NON IE for Firefox and Netscape etc.... if you are using Mozilla firefox. then download the non IE flash player. and also you search a better addon and extension for google translate. voice features

---

nah i just recommend you to use UC browser. it has default IDM. when you see any video in any website it show download.

UC is a good Browser but it's mostly easiest way for virus to hit your PC. UC have a lot of background extensions and cache. cause loaded your PC.
also UC mess with your antivirus. thats why i dont like it.