I’d not do video chats with strangers after only one week of knowing them. Who knows what they are going to do with the video.
But there are ways to know if the person is who she says she is. Ask her to take a picture with something time stamped like today’s newspaper. Or a picture with something you request them to hold. If they insist it’s them on whatever pictures they show you, but refuse to take current, today’s picture, they are likely not who they say they are.
If you realize that they might be anyone, including someone scamming people for money or someone not of a legal age, you hopefully realize that longing for a stranger could be dangerous.
I recommend if you are interested in meeting young ladies, start looking in your area. You have a better chance to actually get to know them