I know he's only eight years old, so I'm going to tailor my remarks to his age and related factors.
More than likely you're going to find a pitching coach to help your son understand more than just throwing the ball. In that regard, the best thing that your son can do right now is the develop a healthy eating itinerary, especially for breakfast. Let your son know now, how important his breakfast mix is, and what time release foods are. For example, juice and, say, apple sauce will digest quicker than say, oatmeal, saugage and eggs. So, in order to benefit form a good breakfast, that intake must digest and serve him all morning long. And so goes his school lunch, supper and so on.
Ok, now on to your question more directly.
A pitcher doesn't release his pitch at a "point" - per se. A pitcher's release of his pitch is more like a cycle, or as we call it in the pitching coaching circles - a phase. In other words, your son must be taught how to start and complete an entire pitching "release phase", from beginning to end. For some pitchers - not all, this "release phase" can start at the breaking of the hands ... separating the pitching hand/arm from the glove hand/arm. On the other hand, some pitchers are coached within another part of the pitching cycle ... phase... called the stride phase. Again, this overall process is finite to each individual and has many disciplines along the way. So, as your son grows, so will his strength in the many disciplines that accompany his coaching.
I especially like his sincerity in the video. A good looking youngster who takes this "show me" and puts his heart into it. As time goes on he'll get a lot better at motor skills ... coordination and ton of other stuff.
Keep the fun in this and he'll wind up some day thanking you big time for the dad that was there for him when he wanted to enjoy and get better at this.
A final suggestion, try not to go this alone with your son. Find a pitching coach who works well with this age group. And don't be surprised if a lot of what you and your son see and experience is very basic and simple stuff. Sometimes this kind of coaching can leave you thinking ... "hey, I could do that.." but don't. Be there to encourage and congratulate your son every step of the way and get him use to dealing with coaches.