Time for the long winded explanation.
Nitrile was created to be a more form fitting alternative to latex gloves when latex allergies were highly prevalent in the medical care setting. Vinyl gloves were first used, but were not form fitting enough and often fell off of the hand affording no protection what so ever, nor did they provide any protection from punctures by needles.
The warnings on the box are more in regards to long term storage rather than while in use, but you probably wouldn’t put your hands in fire or liquid nitrogen anyway and expect to have protection from a thin pseudo-rubber glove. Extended exposure to moisture while still in the box can lead to the material rotting as well as UV sun exposure causing the gloves to dry out and instantly rip. I would often find older boxes of gloves in the ambulance that I was working in and when I went to put the gloves on they would instantly tear. We often cycled out boxes within a month’s time through use, but some of the smaller sizes would sit for extended periods in the cab of the ambulance and dry out.
Nitrile is also more susceptible to acids and don’t offer as much protection with the thinner variants. When I use these chemicals I use thicker gloves, usually 7-9mil. The Venom’s from Lowes are only 6 mil. Do you have a Harbor Freight store near you? These are the gloves I use. They are 12.99 for 50 gloves.
As far as keeping you hands warmer in the winter, these gloves won’t provide too much assistance with that. Yes, they will keep your hands dry initially from exposure to water, but as you work they will also build up sweat and moisture inside the gloves. Then depending on the outside temperature your hands will get cold even faster as water transfers heat 50 or 60% faster than air, which is why people can die in freezing water in 2-3 minutes while they can stand outside in the same temperature air for a half hour or longer.
Luke and Reanna are essentially creating a liner-barrier glove by wearing cloth gloves for warmth and then wrapping them in a Nitrile or Latex glove to use as a moisture barrier. I would be interested to know if they end up using multiple cloth gloves throughout the day as they soak up moisture while they are working. One thing though is that, while Nitrile is more form fitting, it’s not as malleable as latex, so the thicker the cloth glove, you may not be able stretch a Nitrile glove over it, especially if you have larger hands. I wear XL Nitrile gloves on my bear hands, so I need 3XL to go over a liner glove.
Go on WCR and look at some neoprene gloves. I use these on the rare days it gets below 40° here in FL. The seams are not always the greatest and I have had to repair them with rubber cement when they have leaked. Wear the nitrile gloves to protect the inside of the neoprene from getting soaked and change them out periodically through the day. You may go through as many as 5 pairs in a day depending on how physically active you get while working. Keeping the neoprene dry from sweat will also keep them from stinking after a week’s worth of work. If they do start to smell, I use Sink the Stink for my wetsuits and other neoprene gloves I use for Scuba diving.