Mantrailing is a type of nosework where the dog is to track down a target person after being shown a scent item (something that the person has worn or purposely added their scent to) and is to do that by both tracking and air scenting.

This video shows Rain at her 3rd class. She is shown the scent item and she then starts tracking her target. In this instance the trainer also walked alongside the target person to lay a 'decoy trail' and was also the person that Rain watched walk away with her bowl of rewards (treats). Rain did not watch either her target person or the trainer actually lay the trail. At this stage the trail is also only a few minutes old.
When she gets to the playground she sees the trainer and is air scenting before ignoring the trainer and going to her target.

She did very, very good work!