I just got the scarlet2i4 and am learning to record guitar with it, but getting annoyed because i can't find anything online that tells you how to add a video to it. I want to make a music video. Im using MacBook. Help's appreciated
If you are using a Macbook you will already have iMovie.

In a basic sense, you need to export your audio from whatever DAW you are using, then import it into iMovie along with whatever video files you want to add to the audio. Then you use iMovie to edit the video/audio together, and export at the end when you are done.
I did a list of freeware video editors:

The way I do it - I use a camera/iphone to record the video and scratch audio, so I am playing this for the video while I am recording in quality on a DAW, Reaper, Studio One, etc. Then you sync your movie and your audio recording from the DAW in your video editor, using the camera's microphone's sound as sync signal to your quality audio to sync the video with it, then you drop the camera's audio and you're left with camera video and the quality audio recording from the DAW.

iMovie does this really easily, you can make a quick test and see how it fares. When I was on Mac I found that it was all I needed. On PC I am using Sony Movie Studio 13 (the lite version of Vegas Video which costs arm and a leg).

I think Adobe Premiere is the top of the line video editor for Mac. Adobe's new licensing scheme allows you only to "rent" their software, so it is about $20 a month, which might work out if you need it briefly.