Emilio,
Yes there is opportunity there. There is also a lot of competition and a pretty extensive outlay of cash to get started, mostly in software. The recording software and the hardware for the sound and video can be pricey. Depending upon what you are looking to do.
I have been doing it for about 10 years now. The reason that I started was to give my students, I teach at a University in my spare time, the opportunity to pick up areas of web development on their own that are not taught in the classroom. That has expanded to many different areas now as I usually update my videos, about once year if the material has changed.
The key is to stay current with the newer "Best Practices" and focus on quality not quantity. That is where my courses beat the hell out of the Udemy's, Lynda and Total Training courses that are out there. I spend about 20 hours a week responding to emails on questions on my classes from the purchasers. None of the big vendors come anywhere near that level of support. I can attest to that first hand.
I was a member of the Lynda network for over three years, took over a hundred of their classes and honestly never had good customer support from the instructors. The Lynda network responded well to question on their system, but as far as course questions on course content, the responses were really bad, when I received responses at all. Most of their instructors write and record the classes and then they are done. Also I had a big issue with the exercise files that they produce, many of them do not work.
Udemy, they have a lot of classes and some of them are pretty good, but again instructor response not very good and very delayed in responding to course questions. Once example was a question I submitted, and it was a relatively simple question, took 4 weeks to get a response and then the response was incorrect. Udemy can also get expensive, since each course is individually priced. Plus you have to stream the course from their website and the site has been known to have issues with bogging down with too many users. One of the other things that bothered me was the constant barrage of emails from that site. Once you enroll in a class you begin receiving emails, sometimes 5 to 10 per day on classes both from the Udemy Team and the instructors trying to push their other classes. I opted out many times nut it seemed to make no difference.
Total Training had some good courses, but again you are streaming from their site and they were kind of expensive on a per course fee. Now I understand that they have recently changed that model and gone to a subscription based model but I haven't used them under that new system so it would be unfair to comment on that new model.
Sorry for the length of this but I thought I would give you what I had gathered over the last few years.
You will never get rich running a training site, if you take it seriously and want you customers to succeed in their training, it takes a lot of time and effort. But if you enjoy training, and I really enjoy it, we are not in it to make money, just break even if we can. Sometimes event that can be a challenge.
I spend about 10 to 12 hours for every hour on content that I produce. For example, I just finished a 24+ hour course on BootStrap 3. That course took me about 6 months to develop. It covers all the important aspects of BootStrap 3 and how to successfully deploy a BootStrap website. The course was requested from my customers. Trying to keep it priced where most of them could afford it, I priced it at $25.00. It will take me years to break even on that course. But the customers love the course and I have received tremendous feedback on the content.
I hope this helps you out. If you have any specific questions, you can PM me, I will be glad to help you out if I can.