The porn video tag "strech" seems to refer to a type of scene in which the performers engage in activities that involve stretching their bodies, usually for the purpose of pleasuring or teasing themselves or their partners. This can include various forms of body contortions, stretching and pulling on genitals, or elongating body parts such as limbs, neck, etc.
In some cases, it may also refer to scenes where performers stretch their bodies using props or equipment like ropes, bars, or other devices. The goal is often to create intense sensations or visual appeal by stretching the body beyond its normal range of motion, leading to heightened pleasure and arousal.