I knew it.
Yes, it's during the fight to the death between Anakin Skywalker, aka the newly named (though yet to be cooked and cyborged) Darth Vader, and Obi-Wan Kenobi. About partway through the fight, they try to use the Force against each other simultaneously with those gestures. At first, they have a little tug-of-war impasse, before blasting each other away.
Okay, someone else try.
I've lived for over 2000 years, and not all of them were good ones. I've made many mistakes. And it's about time I did something about that.
-The Twelfth Doctor, Doctor Who: Deep Breath