I landed a flying armbar once. (in training) the next time I tried it I smacked my head on the mat hard. Never tried it again because I had too much other stuff to work on.
I always wanted to land a flying triangle but I wasn't really taught it, I just love the heck out of seeing it. Way too old to even play with it now.
But for the flying leg scissors, been doing that since I was a youngster. Done it in competition, in security work, in the gym. I can do it so easy I can cup the back of their head on the way down so as to not let them bounce it off the ground. I can do it as a jump, a slide or a spin (yup). I used to be able to do it as a head scissors (top leg to their throat area with back of your knee - bottom leg angling down their shoulder blades at a 45 toward the floor) but that was only against Karate guys who like to stay in a side stance. I haven't done it since my fifties and won't try again. I actually landed that in competition once. You should have seen his face.
But a regular flying scissors....I can still land that. The thing with any of them is - if it's in your arsenal, you pretty much know when you can land them. And you pretty much know when you ain't got a decent shot either because of position, movement or a particular opponent.
And I sure as heck wouldn't recommend them to everyone.