The vast majority of people who post videos are tutorials on how to create an object or how to use specific CAD software commands to help create an object.

I would first post what CAD tools you are using and then request if there are any questions on specific commands and finally relate those commands to create objects.

For example : if someone who uses SolidWorks in curious on how to make a label, there is a specific process of commands to perform this properly.

Another idea for videos is applying your engineering talents to solve a specific industry problem.

If you are a Mechanical Engineer and you work in the aircraft community and you are working with hydraulics, you can show the process of calculating for pipe diameters, wall thicknesses, material choices, vendors, part numbers, suppliers, and quality / reliability processes that relate to specific industry or ISO standards.

Another idea is to show how to create specific look of rendered parts and backgrounds for advertising and presentations for marketing.

There are many third party tools that import the CAD models and perform renderings to create a realistic 3D image that can then be presented into a background to give a photo-realistic appearance of the model.

Much of this is verging on Art more than Engineering, but is also very valuable in presenting the look and feel of the model before anything has been created.

Many companies value this as it determines the value of the model in the application and can get a buy-in from others for your concept or IP.

Another idea is how to create animations from your models as all working parts go together in exploded views or how it is assembled.

You can show all the moving parts and how they work in relationship to one another.

You can also do cross-sectionals and 'see' inside of the assembly working which cannot be done on the real assembly.

Another idea is how to create drawings and how to use GD&T dimensioning for quality standards and for manufacturing.

Many people know how to create models and assemblies, but very few understand the CAM processes for quality, reduction of cost, and for material choices.

There are many manufacturing processes and the ability to show the critical dimensions in such a way as to maintain quality control and dimensional stability for such things as tolerance stack-up and thermal expansion/contraction widows that do not impede the manufacturer, but also maintain the highest level of quality control.

This is also left as an after-thought in the design process and is where many companies leave it to the manufacturers and often get burned in the long run, but can get burned in the short run when things just don't fit, even though they are dimensioned.

It also happens when something is perfectly dimensioned for one choice of material and fails completely when the material is changed (e.g. plastics).