How to transfer computer videos to the iPhone 6 photo library?

I have an iPhone 6 of 120 GB, iOS 9.3.1, and I want to know how to transfer videos that are on one's PC to my iPhone, without using any 3rd party extension. It's fine to use an iTunes method, I just am looking for some answers (because the internet doesn't like being recent and also likes 3rd party apps).

Use the iTunes method.

Drag your video to iTunes.
Connect your iPhone by cable or Wi-Fi and on the Videos tab on the left in the iPhone menu check the box to sync videos, then select your video and hit the Sync (sometimes it switches to Apply) button.

I don't think it ll appear in the Photo Library but in the Videos app instead.

It's very to do. Here's a step-by-step guide to transfer stuff from your computer to your iPhone: http://open-mobile-share.com/iphone-6-file-transfer-tips/

I usually just email them to myself and then check my email from my phone and save whatever I sent to myself. Lol simple.