If you want to download a video (or even just its sound file) from YouTube but your IDM got expired, you can try youtube-dl-gui.
Here's the following steps for that software's installation:
Go to youtube-dl-gui 's site.
Look for button that looks like the following:
Press that button. Usually, you will be prompted by your browser about this download. Just accept it.
After the file has been downloaded, open that file.
Extract it, usually by clicking the right button on your mouse on the downloaded file.
After that, double click the extracted file.
Usually, it's a file with
.exe as its extension.
You will be greeted by a window dialog that looks like the following button. Just click OK.
Then accept the license agreement.
Next is the right choice for this step.
Press that install button.
Please wait for a moment. And don't worry, its installation process doesn't take a lot of time. Practically less than a half minute, tops.
Now, after that program is installed in your computer, you will see this program like the following
Now, copy url for any YouTube video you want to download. Put them in the the "enter url below" box followed by pressing "Add" button.
And then, press the button with cloud and down arrow on the bottom right corner of the window.
Wait for a while, because you will be shown "Downloads completed!" window when the time comes. Like this.
That's it. You can download any videos you want. As long as you download them at one of these sites.