In the video, the footage was a bit shaky, and opening shot seemed to be off-kitler. The costume choice was poor, and some darker or richer colors might have been a better choice, or some really worn down, more desaturated colors to help bring out the bleakness of the environment, with perhaps some correction & then grading. The blue chair really stood out, too. Something weird was going on with the aspect ratio, and some sweat/panting/closeups of the character that was initially digging would further emphasize his tiredness or tension. The voices were completely out of sync, the music is recognizable, and the overall look and sound of the film wasn't very drab and dark, or ominous, like the dialogue. Nothing seemed suitable.
How do you prevent sloppy work? Identify EVERYTHING that will play a part each scene. Camera, lighting, audio equipment, costumes, set, and everything in post. Know and mark down how each of these individual things will be used, and if they are effective or not. If one is not effective, focus on perfecting that and using the technique that best suits your film. In that clip that you had shown, most of the problems lied in post, but there were still some problems. For one, the costume and prop choice was poor, which stuck out like a sore thumb. If you had chosen a darker chair or spray painted that chair a more grey color, it probably wouldn't have been as distracting as it was. In post, you would have to have spent more time on syncing, trying to match shots through grading, cropping and adjusting the image so that certain shots weren't unbalanced. Also, choose shots for a reason. There should always be a reason for why you're doing what.