He needs to play in a well known summer wood bat league. In many areas there are small college showcases. We have one here in Central Ohio. It is usually held at Ohio Dominican. My son has been invited the last couple of years. These are usually invite only, or coaches choice. They are not publicized, or come one come all. They are attended by scouts looking for players that may be late bloomers or fell through the cracks. Usually it is mostly D2, and D3 athletes, with some guys from the smaller D1's thrown in.
Once a young man goes off to college, the best way to be noticed is to perform. Alot of that comes from playing in a good summer league, playing against good to top talent. It can be more difficult for a d3 position player than a pitcher, but it can be done. As a parent it is pretty much out of your hands now. Trying to send video will probably do no good. Scouts have trusted resources, and they rely on those and their own eyes. Some of it will depend on how he projects to the next level. If he bats .1000 at D3 it does not mean he can hit at the next level.
I am not trying to be harsh, but the best thing you can do now is be supportive and enjoy the ride. If he has the talent they will find him.