Music Videos are very similar in that manner. You need to think, as the editor, how you can use the scenes at your disposal to match the feel and context of the song you're using. Some do this by matching scene changes with the beat or melody, but in that music video, Morgan, you seemed to simply wish to either fill time or get the entire/most of the scenes you were using in that single section of the song. Parts like the corvette scene between "Blaine" and Jorge lasted too long and took me out of the overarching tone of the music video.
Also, the shots in custom games played off as corny, because it was super obvious that "Blaine" was in no danger. I understand that recent Halo titles don't have firefight, and that firefight is pretty unpredictable, but it would have been worth it instead of making the audience watch Blaine shoot past an retaliating enemy offscreen.
If it's your first attempt at making something like this, you didn't do a shitty job. Just remember that the only way to improve in shit like this is to try, try again.