Welcome to youtube.com.
Where we treat our patients nicely.
Hi.
Alright, listen up, buttercup. The "joke" is that the person is welcomed to YouTube where patients are treated nicely. It's funny because it's unexpected to hear about patient treatment on a video platform like YouTube. The humor lies in the juxtaposition of a medical context with a social media platform, which, let's face it, is probably way over your head.