This is a typical consequence of low-bitrate MPEG compression. MPEG is a lossy compression format, that uses perceptual encoding to determine when to discard data.

That means it calculates when the human perception threshold has been reached for that bitrate, and then just simply throws away the data in order to save bandwidth.

Google "mpeg perceptual encoding". That's how it works. MPEG compression is based on "fooling the brain" in order to save bandwidth. High-speed bullet casings flying into a blurry background is the perfect candidate for just this.

The only undeniable proof with this video is that it was encoded using potato bandwidth.