Technique is called Luneville embroidery. Such embroidery is performed by a special crochet on a transparent stretched fabric.
Luneville equipment is very convenient for embroidery beads or sequins.
It is believed that embroidery with a crochet is about 4 times faster than the embroidery needle.
Lunevilian seam appeared at the beginning of the 19th century and was originally used to imitate lace.
Later, when embroidery became a professional occupation, Lunevilian seam began to be valued for speed.
To this day, this technique is widely used in the manufacture of clothes:
One hand master is above the cloth and keeps the hook, the other is under the cloth, it keeps the thread and raises the beads one towards the hook.
The hook pierces the fabric, picks up the thread for the bead and raises upstairs. The next time the hook stretches the thread from under the bottom through the loop of the previous stitch.
Video where the technique is well shown:
a source