How did this happen?

[Handholding587]

Today I got a set of headphones. I was trying them out and suddenly what I was watching in my Android phone appeared on the TV.
I didn't connect them unless by accident. Can any techy people explain?

You can cast video from your phone to other devices using things like YouTube - there is a button in the top corner usually. It is quite easy to do accidentally!

Thank you, I thought I must have pressed something. And I was watching YouTube at the time. If anyone can mess up technology it's me.