OK, yeah, there it is.
The terrifying part (yes, that video wasn't the terrifying part) is that sometimes your Leonardo's little katana gets stuck flopping around outside his shell, a problem known as a "penile prolapse." The good news is that this condition can be treated in your own home. The bad news is that you'll never feel clean again after doing this.
You will, however, gain a greater appreciation for the work of H.P. Lovecraft.
What exactly do you have to do? A quote from this turtle care website describes it:
"With clean hands ... lubricate the organ with KY Jelly, and gently attempt to assist the organ back into the turtle. If this fails ... coat the penis with dry, granulated sugar or honey."
"The most difficult step is learning to live with yourself afterward."
Or you can continue seeing the terror dick every day. Your call.