There is more and more content available on YouTube in 720, 1080 or 4k high resolution. However YouTube does its best to lower the hosting cost and therefore changed the way they store videos of the named resolutions. First off, they reduced MKV container maintenance, so it is now hard to find video of this format in HD.
Secondly, audio and video tracks for the same video are stored separately, which makes it harder for some downloaders to fetch such a video correctly. A good quality YouTube downloader of HD for Windows is such that updates regularly and therefore can handle changes in YouTube smoothly. Such a downloader will be able to download both tracks: audio and video and combine them into one.
There can be multiple reasons why you may need to download HD videos from YouTube, one being the fact that if you don't have a fast and steady Internet connection, YouTube won't allow you to watch videos in high resolution. And sometimes for educational purposes you need a really sharp image which only high definition is capable to offer.
To download YouTube videos in HD we used Airy downloader for Windows (also available for Mac btw). To download with this HD YouTube video downloader follow the steps listed below:
As you can see this YouTube HD video downloader is pretty easy to use. Go ahead and try it out - first two downloads are absolutely free!