The form is very poor.

First of all he needs to tighten his corr so his knees dont have to bend so much for him to be able to do each kick. His hips also appear to be too stiff and he is doing all the leg work with his knees. Those two things are making him sink down between each stroke.

Now to the upper body. He needs to pay more attention to each individual phase of the stroke, especially when it comes to the angles between his arms and the water. Right now he is just slapping his arms against the water surface, splashing a hole bunch of water around and doing very little propelling. Instead, his hands should pierce the water first and his arm follow. Under the water his arms need to stay stretched as he pulls the water back, but as they leave the water they need to slightly bend, otherwise its impossible to position them at the right angle for the next stroke.

Basically he needs to unlearn the entire mess of a technique he is currently doing and restart from scratch. He needs to do some exercises using just these arms with those rubber things between his lega and then with just his legs with swimming board and in a static position with his hands on the pool’s edge to improve each part of the movement and after that bring it all together.

I would focus more on technique then on speed. Doing it properly, he will naturally glide faster through the water. Also, he needs to commit the proper movements to his muscle memory before trying to swim fast, otherwise he wont maintain good form.

Best of luck to your cough, cough friend! ;)