No it's not.
First of all, it's not a licence. UKARA is a scheme set up to ensure that airsoft weapons are being sold to people who are legitimate airsoft players. Secondly, he stated that spray painting the weapon is illegal with a licence [a defence], but it is not. You can spray paint it 2-tone without a defence (but are not required to do so), and you can spray paint a 2-tone to realistic colours with a defence.
Blazin23 - The law doesn't state that UKARA is a requirement, you can buy the weapons without UKARA membership, it's just going to be harder to prove to a retailer that you are an airsofter without it.