Id try tossing a large ground on the motor and see if that does anything. Im sure you have some random 4 gauge laying around. Dont even do it pretty, just toss it on and see if that stops it. If it does, then worry about it looking nice.
From the angle it's hard to tell if that wire is even connected to the mount. There's so much rust around that mounting bolt that I'm inclined to agree with NickR. At the very least remove that mounting bolt and take an aluminum or brass bristle brush to the rust to clean away the rust and oxidation. Inspect and if necessary clean the grounding wire connection then reinstall and see how that works. If that doesn't fix it then it's a different ground causing the issue. For a spark that blue and the interval it's probably coming from a sensor trying to turn on/off like a solenoid control wire.
the spark is arcing from the powersteering tensioner pulley. This isn't a normal 12v spark. The ground is good, it's not rusted...just a bad video and the wire is a little bit dirty. My next tests are going to be trying to find to see if this is an AC power source that's causing it to jump.
For now, looks like possibly a diode is bad causing bad AC sine wave.