Sorry for providing the wrong information in the video.
As a summary, this is a test to test for the presence of Starch, Protein and Fat in the Food.

To test for FAT:
1. Mash a piece of food along with water
2. Put the mashed food into a test tube and leave it in a water bath of 40-50 degree celcius for 5 minutes.
3. Solution turns brick-red if fat is present.

To test for PROTEIN:
1. Cut a small piece of meat and drop iodine solution on it.
2. Food turns blue-black if protein is present.

To test for starch: