How to transfer videos from a Mac to an iPhone?

I have three videos that were recorded onto a different iPhone that I trasferred into iPhoto… How do I get them from iPhoto onto my iPhone?

When you plug your phone into your mac, iTunes should come up and there's an option to add photos (it'll be on the top bar of itunes where it says summary, info, apps, etc). You just check "Sync Photos from iPhoto" and check "selected albums" and also check "include videos." Then all you have to do is look for the videos you want to add and click sync.

You have to locate the videos on your Mac hard drive, If your video is already mp4 video, you can import the mp4 video into iTunes. Connect your iPhone to computer through USB cable, iTunes will recognize the iPhone automatically, and then go to iTunes menu 'File -> Sync iPhone', the video will be transferred to iPhone.

If your video is not iPhone compatible mp4 video, you can follow this step by step guide to convert and sync the video to your iPhone, it's easy to understand and works pretty well for me.