A realistic handheld smartphone video in vertical 9:16 format for TikTok, showing a man with thinning hair in a bathroom under natural lighting; he sprays a hair growth serum onto his scalp, leaving space on the right side for product image placement; after application, hair looks slightly lifted, darker, and fuller with less visible scalp, subtle baby hairs becoming noticeable, no instant long hair growth, documentary style, no filters, natural skin texture, same person same lighting, authentic and believable.