Background/Objectives: To examine whether extending sexual arousal through lengthened erotic video viewing during semen collection improves semen parameters in infertile men. Methods: In this prospective within-subject study, 205 infertile men supplied semen samples in two sessions about four weeks apart and followed strict uniform protocols. In the first session, participants ejaculated after the customary viewing length of erotic videos. During the second session, viewing time was increased prior to ejaculation. Semen volume, sperm concentration, total motility, progressive motility, and morphology were assessed as per the WHO 2021 guidelines. Comparisons were analyzed using paired samples t-test or Wilcoxon signed-rank test and correlation analysis was performed using Spearman’s rank correlation. Results: Median duration of erotic video watching increased from 8 min (IQR: 5–10) to 15 min (IQR: 11–20) (p < 0.001). Moreover, extended arousal was associated with increased sperm concentration (from 19 × 10⁶/mL to 24 × 10⁶/mL, p < 0.001), total motility (43% to 46%, p < 0.001), and progressive motility (33% to 37%, p < 0.001) with unchanged morphology (p = 0.053). Increases in arousal duration exhibited a weak but significant correlation with changes in concentration (ρ = 0.21, p = 0.003), total motility (ρ = 0.27, p < 0.001), and progressive motility (ρ = 0.22, p = 0.002). Subgroup analysis showed improvements in non-smokers but not in smokers. Conclusions: Extended erotic stimulation during semen sample collection significantly enhances sperm motility and modestly increases concentration in men with infertility, albeit without changing morphology. These findings suggest that extended erotic stimulation during semen collection may be a simple, non-invasive strategy to help optimize semen quality in infertile men, especially non-smokers.