As Joe points out in the clip, there is a lot of scope with the dumbbell chest press to execute the exercise in relative comfort by adjusting the position of your hands and elbows. With heavier weights, I really notice discomfort in my left shoulder if I keep the dumbbells horizontal at the bottom of the exercise. To fix this, I tilt the dumbbells slightly towards the chest, which reduces the stress on the shoulder.
Another benefit of using dumbells over a bar is that the separate weights help to balance your strength gains on your left and right sides, which is beneficial to posture. Finally, please note Joe’s closing comment – “make sure that you have a weight that you can control – don’t let the weight control you.”
If you are unsure about any strength-training exercise, start light and rehearse the technique.