The video has auto-generated subtitles with decent translation to english
Ingredients
Whole milk: 100%
Sugar: 22%
Baking soda: 0.1%
Cream: 4% (if not using whole milk)
Corn starch: 0.8% (for a thicker dulce de leche for baking)
Vanilla extract: add while cooling after temperature is 65C or cooler
Method
Add milk, sugar, baking soda, and, if using, milk to a pot at medium low heat. Stir constantly until right consistency.
You can use two pots to speed up the process, start with a small quantity in the second pot, and as it thickens, add small quantities of liquid from the larger one. See minute 3:55 in the video
To check if ready:
Pour a spoonful into a plate, and let it cool for about 30 seconds
Use a spool to draw a line through the pooled dulce de leche
If the dulce stays separated, then its ready. If if flows back into a single pool, it's not ready
To make dulce de leche repostero (for baking):
Dissolve the corn starch with the minimum possible amount of milk (to avoid diluting the dulce de leche)
While stirring, add the corn starch to the pot
Finishing:
Put the pot in a cold Bain-marie, and keep stirring until cool
When it cools down to 65C or lower, add the vanilla extract