You are more likely to have someone click off your video if they see an intro. This is especially the case when it's one of those dubstep over the top kind of intros. It's done too much.
If a person absolutely must do an intro there are way around people clicking off the video.
1. Show a clip from the video before the intro. A funny part. The idea here is you are trying to make them want to watch the video, so the intro will bother them less, or they may just skip it rather than clicking off the video entirely.
2. Keeping the intro only 2 - 4 seconds long will likely not cause too much issue.
3. Make the intro a part of the video. In other words, like an overlay, along maybe with some vocals. "Hey guys! Brabbit1987 here of B-Bunny Gaming back with another episode of ..."