It's really hard to get people to subscribe. There is an age issue here also and a need to know issue. Young people love to be reminded of some cool, new cat video or some stunt video, so they subscribe immediately to sites like that. I'm subscribed to a ton of music YTs. But informative YTs tend to grow at a much slower rate as they are more about education and information and people watch that when they have to or when they need to know something. At that point if the video worked for them, they may subscribe, or they may not because they don't realize they should. Your call to action is good though. It's explicit and straightforward and I'm realizing that there has to be a call to action somewhere in the video. I'm at 55 since I requested subscriptions after you, but I'm okay with that because I have more questions now from people although the views and subscription aren't going up. I guess people want to keep the information for their own use and not share it, lol.