ImReallyANarc, thanks for your response. I actually learned that I can't even download iMovie for my MacBook Air, unfortunately, because it needs the software update of OS X 10.10.3 or something, and the MacBook Air can't support an update that high or something. I updated the highest I could.
I'm assuming MacBook Pros are the ones that come with iMovie already installed. I guess I am just going to continue to edit it on the phone, I mean it's only gotta be 3-5 minutes long and I've already came this far!

I could be mistaken but I thought all versions of OSX came with iMovie for free. I purchased my iMac in 2012 and iMovie was pre-installed.
Also, the $5 app doesn't also cover the desktop version. I learned that the hard way with Pages - bought the app and then couldn't understand why the Mac App Store wanted more money to download it again.
As for iMovie, even if it isn't prepackaged with OSX, I believe it's worth the cost. I've created a couple projects with it and it's a great little program, and I say this having used professional NLE software for over 15 years.