The video description says:

A pet dog's reaction to a family member returning home after 2 years... which in fairness is 14 years in dog years. 

The family member was living and working in Slovenia, and didn't return home to Murrysville, PA last year, because her whole family (except Casey) came to Bled for her wedding.

The schnauzer, Casey, was taken to the vet, the vet saw the video, and everything is fine with her. No worries.