Ive been thinking about this too, and personally if i were to make an intro like clip, i wouldn't put it at the very start of my video, and heres why:
If the viewer decides if he/she wants to watch the video within 10 seconds of starting the video, maybe you should put a short clip from the video (preferably 5-15 seconds) to grab their attention, then put an intro that is 5-10 seconds long max.
This is what a lot of TV shows that i watch and watched have done. some popular shows that do or have done this regularly are: Breaking Bad, Its always sunny in Philadelphia, Southpark, and along with some other shows.
A lot of popular youtubers do this as well if you havent noticed, they will put a clip kind of explaining the video (but leaving the viewer with some interest) or just an interesting/funny/cool part of the video to grab the viewers attention.
For me im probably not going to have an intro, because of the style of videos that i do don't really require an intro, and it also doesn't fit the style of video that i do.
For your videos you may want to do an intro, but for the love of god don't do one of those pre-made free download intros that 90% of every gaming channel uses. That will make most people want to leave the video.
also like i said, try and keep the intro short.