this isn't my instructions, but someone posted this and I copied/saved it:
HOW TO MAKE PERFECT 18+ LOOP VIDEOS
1- Start with a clean, high-quality photo (sharp face, good lighting)
2- Generate the first 15-second clip with whatever action you want (kneel → blowjob → cumshot, etc.).
3- Save the very LAST frame of that video (the messiest / cum-covered one) as an image.
4- Generate the final 5-second “return” clip using:
-Input image → the messy last frame
-final frame → the original clean first photo
-Prompt (copy-paste):
Exact same girl. She is currently covered in thick cum on face, hair and clothes. Over 15 s she calmly wipes cum with fingers, licks them clean, smooths her cum-stained clothes (wet shiny stains remain), fixes hair, slowly stands up, walks back and returns to the exact original pose/smile/framing of the first reference image. Final frame must be 100% identical to the very first photo. Ultra-detailed wet cum stains on skin and fabric, perfect face consistency, smooth return-to-start loop, 4K
-Negative prompt:
blurry, deformed, face change, cum disappears completely, clothes disappear, text, logo, watermark, lowres, artifacts, censored, child, old
5- You now have 2 (or more) 15-second clips.
6- Stitch them together in CapCut / InShot / VN
7- Result → a 30 s–1 min video that starts and ends exactly the same = perfect seamless loop