One further comment---before engaging in this project, you need to make sure your business has the proper intellectual property law foundation---that is a fundamental necessity these days for any small business.

I am planning to have a disclaimer at the end of my video saying this is for general information purposes only and not medial advice. Furthemore I will have another disclaimer on the YouTube channel itself. Do I need to have the discalimer in the description of the video as well?

Unilateral disclaimers generally do not get you very far. You should not rely on the fact that you include these disclaimers in various locations to keep you out of trouble. Of course, the more disclaimers, the better---but once again they do not really protect you much. Most importantly, you would be making a huge mistake by operating this web-site without retaining legal counsel. If you do not have a budget for legal counsel, then your first priority should be raising such a budget. Otherwise I am relatively sure you are going to make a financially disastrous mistake.

I was thinking about changing my business model to a company that provides education on social media, seo and web design to small business. My concern is that if use screen capture of Facebook, Twitter showing how to navigate the site is there a problem with this?

You could have problems under copyright and trademark law, but this also could quality as fair use. It depends on what screenshots you use and how you use them. Also, you would need a patent clearance as there are many patents covering methods for providing education on social medial, SEO and web-design.