The video explains two ways to think about 5x tables and work out the answer:

multiply the number by 10, then halve the result

Halve the number first, then make it a number of tens. Of course, an odd multiplier will require some extra thought when halving

Strategy for Teaching the 5x Tables:

Teaching the 5x tables is easiest if you connect them with the 10x tables.

Since 5 is half of 10, when you have pairs of 5 (eg, 6 fives), the answer will be half that number of tens (eg, 3 tens, or 30).

The bottom line here is to help students to understand the numbers, and work out the patterns themselves. We really do want students to construct their own understanding of the concepts, make sense of the operation, and so reach the answer. This avoids any tendency to teach students a series of steps – an algorithm – which they will probably forget pretty soon anyway.