2001 Sienna rod knock? (with video)

So, bought a Sienna with 250k miles on it, sounded beautiful when I bought it. Day 2, I had a leaky valve cover replaced, as well as spark plugs, and the very next day the Check Engine Light came on, it showed…

C1301- (No DTC found, but seems like a generic code that accompanies VSC off)
P0330- (Knock Sensor 2 Circuit (Bank 2)
P0420- Catalyst System Efficiency Below Threshold (Bank 1)
C1246- Master Cylinder Pressure Sensor Circuit
C1202- (No DTC found, but Google yielded a Brake Fluid Low code)

I figured it was 2 or perhaps 3 issues.

1. Perhaps a leaky brake line or master cylinder. First I refilled the brake fluid, and it’s remained constant since, (but the code keeps reappearing as well). Master Cylinder doesn’t appear to be leaky as far as I can tell. Brake function remains normal.
2. Either the O2 sensors were bad, or the Catalytic Converter was failing. I got it up to speed, used an IR Thermometer, and noted that the outlet hose on the Cat was about 40-50′ warmer than the inlet. Seems to be operating properly, must be O2 sensors or Air/Fuel Ratio Sensor.
3. The Knock Sensor on Bank 2 was bad, (common for Sienna’s) perhaps dislodged by the mechanic during the valve cover gasket replacement. I had scanned the vehicle before I bought it, a couple times over the course of 2 days, and this was not stored in the ECM as far as I could see, (though the Master Cylinder code was).

So, I kind of put it off, figured I’d get around to replacing the Knock Sensor in a couple weeks, replacing the Air/Fuel Ratio Sensor when I was in there, and see if that got rid of the C0420 code… But today I heard a knock coming from the engine. Video (gets worse about halfway through): http://vid58.photobucket.com/albums/g274/fractalcathedral/20170207_143310_zpsi2mf8d9x.mp4 Listening with a stethoscope, it’s definitely the most notable on Cylinder number 2 (far left, close bank).

Is this bad? Is there any chance this isn’t rod knock or main bearing? The Service manual and the Haynes both say P0330 indicate that the knock sensor is malfunctioning and needs replaced, and neither say anything about the possibility the knock sensor is functioning correctly and actually detecting a knock. Is it possible the mechanic f’ed something up? I’d take it to a mechanic to have someone listen to it, but honestly I hate having people work on my vehicles. This kind of stuff happens to me every single time, (take it in, new problem starts immediately), and I get paranoid that they are deliberately sabotaging it to get more money down the road. Anybody got any advice about what to try next?

Edit: Checked oil as well on dipstick, and it was a good amount, and no noticeable aluminum glitter.