Doesn't it seem more likely that you - a person who is interested enough in Autocad that people email you videos about it - searched for something related to Autocad?
Me and my friend have an interest in model aircrafts and drones and often spoke in person about building a new drone/airplane from scratch as fun project and this was the first time that Autocad was even mentioned in our discussion. Another data point we are both old school and would talk about this over beers in the pub rather than through messaging apps.
The only thing linking me to Autocad was that single email I got in Gmail.