That's quite the noise. Smoke at idle? A bad injector can cause you to knock like hell, and smoke like crazy. Also it'll burn up your engine very very fast if you keep running it.
That one is smoking like hell but yours may not, sounds the same though. Tips can break off or stay wide open. I even found a thread where it hydrolocked one guys motor.
I'm assuming you drove it home after, how was it on power and smoke under normal driving. Check engine light?
As far as a test I would pull both valve covers and run the engine, unplugging the injectors one by one ( itll run on 7 no problem) Start with #8 which is the drivers side rear, you'll know the second you unplug the right one.
The proper way to do that is build a breakout box like in this thread, but many people including myself have unplugged them without issue. You could also shut off the truck each time and unplug but I was alone when I did it.
Sorry for linking another forum if that's not cool.
A buzz and contribution test will probably find a bad injector, but not always. A knock like that should be easy to tell by just unplugging.