Young Sheldon: Iain Armitage & Jim Parsons' BTS Video Teases A Huge Finale Crossover

With filming now wrapped on "Young Sheldon," the buildup to the sitcom's finale is getting more and more emotional. Star Iain Armitage has already shared a touching tribute to the show, along with posting a number of behind-the-scenes pictures from the years gone by. Now he's tugging at the heartstrings of fans of "The Big Bang Theory" universe even more by teaming up with Adult Sheldon actor Jim Parsons in a BTS video that teases a huge finale crossover.

In the Instagram video, Armitage looks directly into the camera and jokes, "So apparently there's a new filter that shows you what you look like when you grow up." As he taps the screen, Parsons appears in his place. Imitating what Armitage would do, the older actor gives himself a once-over before saying, "I don't like it," and tapping the screen again.

This is more than just a funny video for "Young Sheldon" fans, as it confirms Armitage and Parsons have been hanging out on set. Parsons was obviously there to film his scenes for the finale, and his presence suggests his character could appear alongside other "Young Sheldon" characters. The working theory for Parsons' upcoming role is that Adult Sheldon will appear in a flash-forward, but he could still have scenes with the likes of Zoe Perry, who plays Sheldon's mom Mary, or Annie Potts, who plays his Meemaw Connie. It's also possible that the "Young Sheldon" bosses found a creative way for Parsons and Armitage to appear in a scene together via something like a dream sequence. While details of Parsons' appearance in "Young Sheldon" are being kept under wraps for now, Armitage has promised that fans of both his show and "TBBT" will be happy with the finale.

Jim Parsons actually worked with Iain Armitage before "Young Sheldon" premiered back in 2017 to help the young actor feel comfortable playing Sheldon and master his mid-Atlantic accent. So working together again for the finale is a very full-circle moment for the actors. And just like Armitage, Parsons says the finale does both "Young Sheldon" and "The Big Bang Theory" justice.

Although he regularly provides voiceover commentary for the show, Parsons' upcoming role in the finale will mark his first physical appearance on "Young Sheldon." And to make it even more special, he will be joined by his "TBBT" co-star Mayim Bialik, who plays his on-screen wife, Amy Farrah-Fowler. During an interview with Entertainment Tonight in March, Parsons confirmed the pair had finished filming their scenes, telling the outlet it was everything he hoped it would be. "It was beautiful. It was even more beautiful than I expected it to be," he said. "One of the reasons I was excited to do it is because what they wrote is so sweet and I think they worked Mayim and I into that show so beautifully. I hope everyone agrees."

Parsons added that he was really happy to revisit the character he played for 12 seasons on "TBBT," even just briefly. It's currently unclear how much of "Young Sheldon's" final season Parsons and Bialik will appear in, as the last two episodes of the sitcom will air back-to-back on May 16. They may appear in both or just the show's very last installment.