I've been hearing about this "challenge" from a friend since a while. In Mr. Kunwar's experiment what I pointed out is he is immersing one glass to another. May be two glasses have same capacity. He can check the reproducibility of his experiment by taking, say, 1000 mL of water in a bowl (make the bowl full) and then place glass having 100mL of water. Exactly 100 mL of water will displace from the bowl. He just can't fail archemedes theory with just one 2-glass experiment.

For his experiment, when he immerses 100 mL glass in glass containing  25 mL water, water may not overflow, but the level must rise. If he measures the change in level (say x cm), will not this length if turned into volume by multiplying with circular area of glass give the volume of water corresponging to almost 100 mL of water? Think about it guys !