One of the easiest ways to watch YouTube videos offline is by using the YouTube app itself. Simply go to the video you want to watch and tap on the “download” button under the player. The video will then be downloaded to your device and can be accessed in the “Library” tab.

Another option is to use the YouTube Premium service, which allows users to download videos and watch them offline without any ads. YouTube Premium also offers access to exclusive content, background playback, and access to Google Play Music for an additional fee.

Lastly, third-party apps like Documents by Readdle, TubeMate, and Video Keeper can also be used to download YouTube videos. However, it is important to note that these apps may violate YouTube’s terms and conditions, and could potentially harm your device.

In conclusion, downloading YouTube videos to your iPhone camera roll can be risky and illegal. It is always better to access YouTube content through legal means, such as using the YouTube app, YouTube Premium, or other verified and trusted video streaming services.