1,2,3,6,7,10… 6 ordered numbers, so median is the mean of 3 & 6, that is 4.5 =（3+6)/2; but is also the number in the middle, so median is 3 numbers below (left) & 3 numbers above (right), halfway between 3rd and 4th number, that is 3.5 =（1+6)/2; for 6 consecutive numbers 1-6, both definitions for median are similar, that is 3.5 =（1+6)/2 and 3.5 =（3+4)/2; in other words the shortcut only gives the position, between which terms is the median
At 5:25 he says (6+1)/2 = 3.5 is the median based on the formula (n+1)/2. But from the list, the average of 3 and 6 is (3+6)/2 = 4.5. So which is it?
1,2,3,6,7,10… 6 ordered numbers, so median is the mean of 3 & 6, that is 4.5 =（3+6)/2; but is also the number in the middle, so median is 3 numbers below (left) & 3 numbers above (right), halfway between 3rd and 4th number, that is 3.5 =（1+6)/2; for 6 consecutive numbers 1-6, both definitions for median are similar, that is 3.5 =（1+6)/2 and 3.5 =（3+4)/2; in other words the shortcut only gives the position, between which terms is the median