Despite it's downsides (mentioned below), any money you do earn as a result of this promotion is dropped into your account as cash, not bonus, and so has zero wagering requirements attached and you can even choose to simply withdraw it if you wish providing your account meets the minimum withdrawal amount for your chosen payment method.
At present the casino states that this deal is only running for the month of August but it has been offered several times a year for a long time now so don't worry yourself about rushing to participate!
I do enjoy cashback promotions - sometimes I'm not even aware they are running and just log into a site and find a chunk of money sitting in my account when I was intending to make a deposit! On the other hand some casinos require you to opt in to these promotions and you can end up missing out for no good reason if your not aware the offer is running... Jackpot Joy is one such casino unfortunately and you'll need to choose the "Take Part" option in the promotions page before beginning to wager otherwise you'll get nothing. I tried to get casino support to opt me in after the fact the first time I tried to take part in this promotion and was advised it was simply not possible to do it this way.
It's not the most generous cashback deal in the world either, you must wager £50 over a qualifying weekend to receive anything at all - the minimum £5 - but there's also a ceiling limit of £10 as well, so any losses over and above £100 will not award any additional cashback. You'll have to wait for it too, all Jackpot Joy are willing to promise is that you'll receive your money sometime between Monday and Thursday the following week.