"Deep-blow" in the context of a porn video tag refers to a specific sexual act, more commonly known as deepthroating. It is an advanced oral sex technique where the performer, usually a woman, takes their partner's penis deep into their throat. The term "deep-blow" emphasizes the intensity and depth of the blowjob being performed. This is considered a high level skill in the realm of oral sex and is appreciated by many for its intensity and stimulation. This act may not be suitable or enjoyable for everyone due to potential gag reflexes and discomfort involved, which is why it's often mentioned as a specific category or tag within porn videos for those seeking such content.