The content of a video determines how successful it would be on YouTube. Alot of factors determine how successful the video will be. Here are some:
The quality of your video is important, you do not want to give out poor quality videos, this will make viewers leave in the first few seconds of the video. What’s even worse is that they might give you a thumbs down, and too many of that will rid you of viewers and followers.
Your intro is also very important, the impression you make at first determine if your viewers stay or leave.
Keep it simple and straight to the point, do not beat around the bush, go straight to the point. Including background music also help to grab the attention of viewers and the video wouldn't be boring.
Essentially, the content quality of your video must be high or otherwise, even if viewers were attracted in the first place by whatever hook you used, they won't return. There must be something outstanding about your video in competition with the many thousands of others going up each day. You can improve the presentation of the video by ensuring you have a decent camera, preferably with 4G capability, and do your videoing in a properly lit environment.
That said, you want your video to get to the point quickly, don't pad or beat around the bush, say (or sing) what you want to say straight out. You've only got about 3 minutes to capture the attention and make the viewer want to come to see you again. So keep it short and make every second count, visually and with the information you want to convey.