They pay for everything for the cats out of their own pockets or with contributions from their YouTube fans. They came found a stray ginger kitten by the garbage cans in this video, who was terrified yet hungry.
Stoyan dashed home to get food and a cat carrier, while Dessy waited close by to keep an eye on the kitten, as it was a terrible environment for a little animal. There were a lot of dogs and a major main road nearby.
So they fed her, gave her time to adjust to their presence (she had probably never been around humans before), and then picked her up and drove her home.
When she arrived home, she was greeted by their two cats, Sopolcho and Bagheera, but the tiny one was still terrified and need special attention. She was soon purring, relieved that she was finally secure.
I believe she was now enjoying the attention she was receiving, particularly the food, which she had obviously not eaten in a long time.
Stoyan and Dessy had come down that street at just the perfect time, and there was no way they could have left her behind.