4k Video Downloader

Really useful software when it comes to downloading full HD or even higher quality videos. In newer versions, it also supports 60 fps videos. Free version works fine, you can pay for downloading whole playlists of videos.
So, 4K Video downloader is much better then other paid products, it works very quickly, and downloads in excellent quality and I can only recommend it.

I've tested 4K Video Downloader, YouTube By Click, KeepVid.com.

4K Video Downloader offers to choose from various resolutions and formats. Moreover, 4K Video Downloader allows to download video subtitles too (if video subtitles are available). I also prefer 4K Video Downloader user interface rather than YouTube By Click interface.

4K Video Downloader offers standalone installer that isn't bloated with addware (bloatware), contrary to YouTube By Click, which offers bloatware and you must be careful not to install that bloatware.

I've used to like KeepVid.com, but KeepVid.com doesn't offer downloading high resolution (1080p, 4K) for some videos. Also KeepVid.com was unable to download subtitles for some videos. In all of those cases, 4K Video Downloader worked just fine.

As of 2015-01 I'm going to use 4K Video Downloader as my primary YouTube downloader.

I recommend you try 4K Video Downloader first before trying other YouTube downloaders.

[Edited by HughTash, January 21]

Horrible privacy policy. Make sure you read it before using.

The best downloader! The price is so small and you get a license key for a lifetime! It always works flawlesly. If you don't want to spend money -there is always a free version. Highly recommend.

Good app, i have it for several months already. It saves me lots of time because i like to watch videos in my car while travelling.

Turns out youtube itself does not support audio quality at or near 320 kbps so when I download videos with this app and they do not have high quality audio, it was actually Youtube's fault and not 4K Video Downloader.