It depends on what the video is about and if I'm watching it on my phone while being on the move or not.
But usually it goes like so:
- If the video is showing how to do X with the coding involved and it's something I haven't done or want to have as an example on my laptop then yes I will code while watching it.
- If the video shows codes and explanations around say paradigms or how he/she goes about doing A or B tasks then I would just watch and see how he/she thinks about the problem(s) to solve and how he/she writes the solution (read code).