My take is it is inferred box office receipts.

When they ‘four wall’, they pay a single fee to rent the entire cinema (the ‘small fee’ they paid to a friendly cinema owner.

They then ran 5 viewings.

So they are claiming being sold out for each of the viewings. (5 * seat capacity * ticket price), but didn’t actually pay themselves for all the tickets (no revenue - small fee = small loss)