I think a high quality airsoft gun or plastic molded gun (aka red gun)
based on your real gun can be a good training tool. Some cheaper airsoft guns are modeled after real guns, but may not have the same measurements. The red guns would be your best bet in terms of feeling real. I would say to practice your CQ and reactionary shooting with a real gun and real bullets on the range, and use the airsoft or red gun for non-range training, such as room clearing or disarming techniques.
Depending on your training you may want to consider a red gun instead of an airsoft gun. While the triggers on red guns cannot be pulled, they are one solid piece of plastic and are more durable than most plastic airsoft guns.
Finally, training off of videos by yourself is hard to do correctly. You don’t have an expert to watch you and make sure your technique is proper. Paying for a training class can cost big bucks, but can really pay off!