Roger Corman ping.
Thanks. Attack of the Crab Monsters is a classic. Scared me to death when I was a little kid.
The question is how I would have watched it. It came out when I was five. My parents would never have taken me. My best guess harkens back to the golden era of early tv. I remember life without tv; the idiot box had been invented, but you didn’t have to be too far out of the big city to be out of range. One of my earliest memories is of my dad taking me to see what he claimed was the first tv in town. I suppose ranges had increased to the point that a really determined viewer could get enough static to pretend he was actually watching something.
Eventually an independent station opened 20 miles away and we got decent reception as long as the weather was good. In those early years, channel 4 used to show a monster movie every day about the time kids were getting home from school. This was early independent tv; they showed the same movie every day for a week, then rotated in another one.
This is how I learned that radiation causes gigantism. For some reason, I found the giant crabs particularly scary. It might have been because the crabs liked to bite off heads, which is how they developed their superior mental capacities. This might stand as Roger Corman’s greatest contribution to the canon.