Hey, Dude, here's another fan!
I was not so fortunate as you and the other respondent I never came across FE on TV when I was a teen (the 60s). I can tell you that had it been picked up by the local late night horror movie program in my hometown, it would have been cut to ribbons.
But it wouldn't matter. It's got too many charms to not thrill the pants off of this sweaty-palmed, pimply-faced teenager.
I mean this is THE most ambitious low-budget independent sci-fi/horror pic of the Sixties, when just as you think that the only monstrous things you will see are some glowing protozoa, you get a standard-sized gnarly creature, then a building-sized version.
Too cool.
And then there's the babes.

I can't believe this has been shown on TV and I've missed it! I saw this in 1979 on a local Chicago channel, I was 10 at the time and it scared me so much, I had to turn it off and hide under my blanket. Which dismayed me, because I considered myself a horror movie afficianado (yes, at 10). My dad had been taking me to horror double features at our neighborhood theater since I was about 5, and I also recall watching "Night Gallery" and "The Night Stalker" with my parents. I also had night terrors, so it was all the same to me.
So now I just got the name of this movie again - I've wanted to see it to the end ever since that night 31 years ago. I just added it to my netflix queue, so I'll be seeing it again soon! Yay!