Does the GX8 latest firmware solve shutter shock with the 14-140mm lens?

Not quite right. On page 5 of the shooting menu you have the option to set the electronic shutter to Auto, on, or off. You have to be aware of your silent setting as well as the two interact.

If the menu item is set to auto, electronic shutter is automatically used for shutter speeds from 1/60 to 1/320, and mechanical shutter outside those speeds (assuming silent is set to off, silent on forces electronic shutter all the time)

If electronic is off you get the mechanical shutter all the time unless you turn silent on, which overrides the menu setting and forces electronic with no sounds

If electronic is on, you get electronic with sounds (focus confirm and selectable shutter sound) if silent is off, and no sound if silent is on.

Frankly I find the whole shutter shock thing is vastly overblown, and used as an excuse for every blurry photo! If you are looking for the last pixel detail and might use shutter speeds between 1/60 and 1/320 it might be worthwhile using the automatic feature (you might then get rolling shutter effects, I know. You might also get struck by lightning while taking the photo ;- )

If you print 9x12 inch you won't notice the difference.

However the issue has gained a cult following on here, mostly from people who don't even use either a 14-140 or GX8, and credit to Panasonic for responding with this software work around.

I don't think that in normal use, without using the auto feature you will see a shutter shock problem, anyway. However if you did, the software update would fix it.

Sorry, I can't help with the video question

tom