You're VERY entertaining Peel! You've led a sheltered life (coming from a Democrat family used to buying selected cuts on Styrofoam platters) of "neatly shrink-wrapped meat", but I still LOVE your writing style. I'll try to answer you as "dead serious" as I can, and w/o mocking or making fun of your self-admitted lack of knowledge in this area. BTW, I just told my Amazon Echo to play "Born Free" by the Chairman of the Board (Frank Sinatra) as I type this I had the movie on VHS!
Yes it's normal for harvested animals to quiver. The old expression, "Runnin'-around like a chicken with its' head cut-off" is based in REALITY! Chickens can run headless until they bleed-out. Hogs can shake like this OR NOT and deer can run like hell for 50 yards OR NOT (a lucky spine shot), dead on their feet from a well-placed shot into their "Boiler Room" (heart/lungs area), and not pile-up (fall-down) until the loss of blood translates into loss of oxygen to the brain. Pheasants sometimes need their necks broke after being downed by a scattergun blast.
My Hog Hunters all wear sidearms for dispatch shots to the brain, should the need arise. We frown on dinky 9mm rounds and ask them to bring .357 mag OR BIGGER to dispatch an animal as quickly as possible, the humane way, as a true Sportsmen would. On this hunt one Gent brought his Ruger .454 Casull & used it for a dispatch.
There's excitement & congratulations from fellow hunters and the professional guides, but no "Blood Dancing". I've had hunters say a prayer to themselves before posing with their harvests. It's not that uncommon. Hell, I've done it after a long day tracking.
The 2nd hog harvested in the above video was taken with a single .308 soft point in a quartering-away presentation that resulted in a one shot harvest. These two women are friends of mine & fellow NRA instructors that realize that some folks will not like the video. That being said, they still gave me permission to share it so other women would become empowered, and not let themselves be refused the opportunity simply because of having different sex organs. Lorraine is a deer hunter, and this was her first hog. The pair field dressed Jackie's hog under expert supervision from our guides. There's a You Tube video of it here, so don't click if yer squeamish:
I fully realize that some folks, who've been sheltered from what goes into harvesting animals, will find hunting "gross". Hunters, since prior to the Revolutionary War, have been teaching marksmanship to Patriots that have defended this great experiment of a Representative Republic. Having 2A people go hunting is more natural than most 2A people think. In Pennsy they close the schools for the start of deer season and 10 year olds go with Moms & Dads to learn the ways of the field.
May you be blessed with many enjoyable experiences in whatever form of harvesting suits you. I too enjoy finding steaks & burgers ON SALE in the meat case WRAPPED IN SHRINK WRAP at my local Shop Rite. Friday they had ground beef for a $1.99 pound
Respect, ALL WAYS & ALWAYS!
Rosey