The Scottish actor, who plays Dr. Owen Hunt, steps behind the camera for the first time as a director on the Feb. 3 episode, titled "Don't Deceive Me (Please Don't Go)."
"It's really scary to take on something big like this because it's so new," McKidd, 37, tells PEOPLE, "but everyone brought their A-game to really support me, and I'm blessed that they did. They know how scary it is."
At the same time, "there's also a lot of fun to be had," admits McKidd, who had directed a few Web episodes of the series to get his feet wet. "[The cast] are poking fun at me being the big adult in the director's chair, you know! What I love about acting is you get to be kind of childlike, and people found it funny I was pretending to be a grownup."
So how did McKidd do? "I never doubted he would be great," says Kim Raver, who plays Teddy Altman. "The crew was so excited because he knew exactly what he wanted, he got it done and he also knew how to speak well with actors."
For example, in a plotline involving Dr. Richard Webber learning how to use Twitter, McKidd told actor James Pickens Jr. to consider departing from his usual serious delivery. "I said, 'Let's see him highly caffeinated and hooked on Tweeting. Let's see him play with that,' " McKidd says. "He really enjoyed getting to explore that kind of machine-gun-fire, rapid-dialogue that he doesn't usually get to do."
McKidd wants more chances to direct in the future. Series creator Shonda Rhimes "called me and said she loved it," Mc Kidd says. "Hopefully they will give me the chance again and I will embrace it with open arms and hopefully do an even better job."