What @UnicornHunter said but also...on-take of new customers was...

What @UnicornHunter said but also...on-take of new customers was far higher in H2FY17 (as seen with massive growth in cash receipts in Q3 and Q4), therefore expenses associated with production costs of videos for the plethora of new customers (here & in US) are expensed to the PnL as they're incurred (most expenses are incurred when the film crew film the videos, then weeks later when they're edited) ...whereas revenue is realised to the PnL proportionately across the 12 month membership (if they were paid upfront).

Assuming a good proportion of those new customers in H2FY17 paid their 12 month membership/fees upfront, this leaves a situation where expenses are recorded earlier than revenue for that customer. This would account for a good deal of that declining gross margin. As stated earlier, other one-off expenses associated with US expansion would account for that too

All IMO DYOR