Shoot a clip through a plastic lens after the fact. Colors are pushed hard, shadows crush to black, and the corners fall into a dark, color-shifted vignette.
Color and shadows
Saturation pushes colors away from gray, up to double. Crushed Shadows darkens the lower half of the tone curve for the punchy, contrasty look of cross-processed film.
Corners
Corner Color Shift and Vignette act from the center outward, so the subject in the middle stays clean while the edges carry the flaws. Bright outdoor footage with color, such as beaches, streets, and festivals, suits the look.