How is non-commercial use defined? Does it only mean that I am not allowed to give XMPlay away for money?
Imagine that I want to use XMPlay ...
- ... on a music event or in a club/discotheque,
- ... on a computer in a pub or barber's shop (to offer background music to guests/customers),
- ... on a company's computer in my office just to listen music while working.
Is any of this commercial use (and not allowed by licence)?
Commercial use of XMPlay would basically be where it is used to make money. So your 3rd case (listening to music on your work computer) is fine. The 1st case would generally be commercial use, ie. XMPlay is being used to make money. The 2nd case could be considered commercial use too; the customers aren't specifically paying to hear music, but perhaps it's creating an ambiance that's conducive to drinking and hair cutting

Anyway, if we're talking about an individual or small business making a bit of money through using XMPlay at an event, that won't be a problem. It is only really where larger businesses/sums are involved that prior agreement would be needed.