Very quiet engine knock? + video clip

Is it normal for the prius engine to sound like this? Not loud knocks like 'Service Bulletin for Engine Knocking at Startup T-SB 0012-10' but clicking, coming from near water pump.

2012 Prius Four solar + HUD options
84k on engine
78 gasoline
11 mile daily commute (2 hwy miles)
3k til engine oil change
No ATF has ever been drain + refilled
Water pump never changed

Few things to point out, temp dropped to 55 degree overnight. Last gas trip- 3 gallons of 78 gasoline at another place for 20 cent cheaper. Everything else such as driving pattern, MPGs & etc has stayed the same.

Any help will greatly appreciated, thanks.

 

Thanks for helping

Toyota 0-20

 

Crap I meant 76 gasoline top tier brand not 78, sorry about that.

Haven't changed engine filter yet, bought car from Carmax which filter was fine before buying. Not dark, not clogged or brown yet, it's been driven 2000 miles since I bought it.

No signs of mpg loss it either. car gets a 30mph drive for 10 mins before getting in highway so no rapid acceleration during mornings.

Hope someone can also go to their Prius and compare their engine to the sound mine is making. I have a feeling this could be the normal sound and I'm just being too critical of this.


Thanks again for your help, much appreciated.

 

From what toyota's website said using VIN # lookup, it's been changed with toyota 0-20w on all maintaince from previous owner in toyota dealership.

 

Thanks for looking into this with me. I've dumped a bottle techron fuel injector cleaner in the tank last week and been pushing the pedal driving under power mode to flush it through the fuel injectors. Don't know anyone in my social circle (lack there of) that owns a gen 3 prius to do a compare.