Thanks! I may not post or comment much, but I'll stick around for the foreseeable future.

these types show up on EBAY sometimes and you might find someone with drivers listed separately but the Chinese ones where often sold as a kit and NOT separate

In the case of the video it's just an old type of governor. Because at startup the RPM is not at the set value, the engine gets maximum injection and because it's not yet at speed, the air/fuel mixture is incredibly rich causing the smoke.
This can be prevented with basic electronically controlled injection systems, which don't just put fuel to 100% on startup.

A similar situation happens when you have a turbodiesel that you suddenly load up. First the governor opens, and only after the turbo spools up, you'll have a good air/fuel ratio again, and the smoke fully disappears.

Petrol engines should never smoke. If they do, they're burning oil. During starting you definitely get exhaust gases coming out of the tailpipe but no smoke. Water vapor can very much be exhausted, if it's quite humid and cold. but that often goes away within 10 minutes or so.

I know that car petrol engines starts to exhaust gases and smoke only after the starting and not during the starting judging by the noise of the exhaust. I've heard this with my father Subaru XV crossover.
Why is this?

Eric, thank you for stickin around. It's a pleasure to have you here.

Here are Iwasaki LED lamps:
https://www.eye.co.jp/lighting/sources/led/

So why sodium iodide have lower vapor pressure than metallic sodium? (In HPS lamps, the sodium vaporizes easily, while in my BLV Colorlite HIT-DE 70W Orange lamp, it takes very long time to vaporize, and the arctube have heat reflective coatings at the ends).

Bare metal is just different material than a compound containing it. The bare atoms tend to attract each other way stronger than the molecules of thallium iodine. The valence electrons like to pair orbits with others. In a bare metal it leads to forming the crystalline structure, but when paired with a halogen atom (I), the electrons are extremely happy so not much forces to other molecules. So easy to release with just a little shake (aka not that high temperature), hence the high vapor pressure...

Normally the shut down should cut off the fuel injection first, regardless what fuel injection control it is using (pure mechanical, hydraulic governor, electronic,...; all have an input lever/signal to cut off the fuel for engine shut down). Air intake choke is only a backup method (it is able to stop even a runaway engine in case it starts running on its lubricating oil or so), it is to be activated only with some delay or when the fuel cutoff is not effective.
Plus you don't want the unburnt lightweight diesel fuel to dissolve and wash out the lubricating oil film on the cylinder walls after the shut down, so it is important to stop the fuel first before the lubrication is stopped (so the engine itself spooling down).

So unless the engine is faulty (e.g. misaligned shut off sequence control cutting out the air before the fuel, or the engine is actually burning oil or so,...), there is no reason for any smoke at shut down.

Metallic thallium have so low vapour pressure, that thallium spectral lamps like that of Osram, have their arctubes enclosed in a metal cylinder for heat conversion.
In contrast: Thallium iodide have so high vapour pressure that green MH lamps usually don't have heat reflective coatings at the end of their arctubes, can run up and hot restrike very fast compared to white MH lamps of the same wattage.
How this is the happens?