There's a red flashing or pulsating banner on top of my iphone screen?

I was going to watch a video on YouTube and almost dropped my phone and I may have clicked on something and then when I looked at my phone their was a banner at the top of my screen and I can't take it off When I click on it it takes me to my YouTube app but i don't know what's going on? Is it like recording me or something?

No it means that the app is still running. Double tap the home button to bring up your running apps, scroll over to the YouTube app and swipe upwards to close the app. Hope this helps!