Apple is making it harder and harder to download YouTube content, but we do still know of a few ways to get that content on iOS 10 and iOS 11.
We're using Documents 6, which is available only in the UK App Store. We're unaware of an equivalent for US users.
However, an alternative for US users is to download those videos to a PC or laptop, then transfer it to your iPhone or iPad's Videos app.
We also explain explain whether it is legal to download YouTube videos.
On your device, go to the App Store and search for "Documents by Readdle". This is a free file management app that'll let you download YouTube videos.
Once installed, launch Documents and tap the bottom-right icon that looks like the Safari icon (a compass).
This will display a web browser where you can search for "savefromnet", without the quotation marks.
Tap on the en.savefrom.net link in the search results.
Go to YouTube
You need to get the URL - the web address - of the YouTube video you want to download. One of the easiest ways is to launch the YouTube app on your iPhone.
Find the video you want and wait until any advert has finished playing and the video begins. Tap on the video to show the controls, then tap the share icon (an arrow pointing right).
Now tap Copy Link.
Return to the Documents app, and tap in the Link box just below the savefrom.net logo. Tap again to bring up the Paste option and tap that to paste in the URL you copied from the YouTube app.
You will see a green Download button with a drop-down menu to the right that offers various resolutions, so you can choose the quality you want. Resolution may be limited to 720p, so you might not be able to download the original quality if the video is in 1080p or 4K. But for watching on an iPhone screen, 720p is acceptable.
Tap the green Download link next to your preferred quality and rename the video if you want to. Now tap Done and the video will download. It's best to do this via Wi-Fi, not on mobile data as videos can quickly use up your monthly data allowance.
Tap the arrow facing down from the menu at the bottom of the screen and you can see the progress of the file download.
Once downloaded, return to the home screen of the app. Make sure you're in the Documents tab (bottom left icon) and then tap Downloads. There you will find your downloaded videos.
You can watch the video from here but if you prefer you can also save this to your iPhone or iPad's Photos app (not the native Videos app, unfortunately).
To do this, tap on the three blue dots below a video, then choose Share. From the iPhone's Share menu, choose Save Video and accept the permissions to allow the app to access your phone's Camera Roll.
Now you can just head to the Photos app and watch the video.
Download via PC or Mac
If you don't like the hassle of copying and pasting links and switching between apps then there's an easier way if you have a PC (or a Mac) using Softorino's YouTube Converter 2.
Head to the YouTube Converter website and download the version you want - Windows or Mac. The downside is that this app isn't free - it costs $19.95.
Connect your phone or tablet to your PC and tap the 'Trust' option if asked.
An alternative is YouTubeByClick which is free with an optional premium mode that gives you more control over the quality of the file you download. This won't transfer videos directly to your iPhone or iPad, so you'll have to do that via iTunes or other software.
Transfer to iPhone
To download a video using YouTube Converter 2 or YouTubeByClick, head to a web browser and copy the URL of a YouTube video you want to download. The video will automatically appear in the app and you can copy more URLs and build up a list of videos to download.
You then need to choose the quality for the videos. Although you can select 4K, it's more sensible to choose 720p or 1080p as no iPhone or iPad yet has a 4K screen, and your chosen video may not even be 4K.
In YouTube Converter 2, click the Convert and Transfer to iPhone button and the videos will be downloaded and transferred to your iPhone's Videos app. It can take a while, so do this well in advance of needing the videos.
If you download with YouTubeByClick you'll need to use iTunes or another app that can sync video to your iPhone or iPad.