Can I detect unique people in a video? I am having a video feed with multiple faces in it. I need to detect each face and the gender as well and assign the gender against each person. I am not sure how to uniquely identify a face as Face1 and Face2 etc. I do not need to know their names, just need to track a person in the entire video. I thought of tracking methods but people are constantly moving and changing so a box location can be occupied by another person after some frames. 

I am interested in a way where I can assign an id to a face but I am not sure how to do it. I can use Facial Recognition Based embedding on each face and track that. But that seems to be an overkill for the job. Is there any other method available or Facial Recognition/Embedding is the only method to uniquely identify people in a video?
Can I detect unique people in a video?

Yes. However, for some applications commercial systems are not good enough: German source
The concepts you are looking for are:

Optical Flow: for two frames, define for each point how it moved
Object tracking: given a single object in one frame, find it in the next. Optical flow helps with that.
Object detection: look at YOLO / SSD. Small introduction here.