QUESTIONS ABOUT DOWNLOADING VIDEOS FROM WEB PLAYERS
IDM does not show a video download panel for some videos but works for others in the same site. Why does it happen?
Some videos (for example many large YouTube clips) are protected by Copyright and use special protected protocol. It is restricted to save any data recived by this protocol. IDM does not support it for legal reasons.
To check that this is the reason why video is not shown, you need to open "Options->General" IDM dialog and press "Edit" near "Customize IDM Download panels in browsers".
Then check "Show download panel for protected content which IDM may not download" option (arrow 1 on the image) and press "OK" (arrow 2 on the image).
Now when you play such protected video in a web player, IDM will show a video download panel on browser's menu bar. When you press on it, IDM will try to download video by unprotected protocol instead and sometimes it may work. Otherwise IDM will tell that it cannot download this video for legal reasons.