Heh! I caught that pronunciation, too. Caused me to wonder.
I've found that there are a few regional differences in pronunciations that are curious. For example: Where I grew up (east of Modesto, CA) farmers and everyone I knew pronounced almonds as "ammuns" (with a as in cat, u like e in the), even though all the outsiders pronounced it as spelled. I've changed to pronounce the "L", but when I visit with friends from that area, we always revert to the silent "L" version. Who knows where different pronunciations start.
True enough but the "willies" thing is not apparently regional. It seems to stem from some kind of assumption that the jeep was invented by Willy somebody. Makes me wonder if the guy in the video, or his dad, ever drove that Willys into the Sierra's.
Another note: that was the model used as George Patton's jeep in the movie, even though it was a 1953 model. Characteristic high hood due to the fact that it was the first OHV model. All the WWII MJ's were flatheads.