I'm not sure if Dipuraja has recently edited it, but this is the text accompanying his video:
"To make base gravy you need onions, green peppers, 3 or 4 green chillies, a handful of corriander, 1 or 2 carrots, cooking oil, salt (1 teaspoon for the amount I have shown you) more would be required if making larger amount of gravy. 2 tablespoon of blended garlic and Ginger. Then add some water and boil for 30-35 minutes. After 35 minutes of Boiling the onions, add 2 tablespoons of mixed powder and half a tin of plum tomatoes. Cook for a further 10-15 minutes. Once you've done that leave to cool down. Then blend the gravy, water can be added to thin the gravy. Now you are ready to cook your curry. Can be frozen but only keeps for 2-3 days or loses the flavour"
So it seems that water IS added to the veggies in the initial stages of cooking.