Lots of times vloggers like to start with an intro or even just saying hello and who they are. Personally, I prefer just jumping straight into what I want to talk about. Many people click away from videos if they're not immediately interested.
I like to set up my videos like a cold open on a TV show: I start talking about the topic right away, then I find a good spot to put in my video intro (having one is risky, I know), and then continue on with a more detailed main feature.
I think having an intro is good as long as it's something unique to you. It's really helpful in creating an identity and how your viewers perceive you, but I'd rather hear every video starting with "Qazzup" than "Hey guys, it's Qazplm."