They will not be caught, because they are not watching it.
There are specifics
The law says you need to be covered by a TV Licence to:
- watch or record programmes as they’re being shown on TV, on any channel
- watch or stream programmes live on an online TV service (such as ITV Hub, All 4, YouTube, Amazon Prime Video, Now TV, Sky Go, etc.)
- download or watch any BBC programmes on BBC iPlayer .
Do I need a TV Licence to watch online, including on YouTube?
You need to be covered by a TV Licence to watch programmes live on any online TV service - such as ITV Hub, All 4, Amazon Prime Video, Now TV or Sky Go. You don’t need a TV Licence if you only ever watch on demand programmes on any TV service apart from BBC iPlayer.
You don’t need a TV Licence to watch videos or clips on demand on YouTube. But you do need a TV Licence if you watch TV programmes live on YouTube. An example of this would be watching Sky News live. But it isn’t just live news or sport which needs a licence – it’s any programme which is part of a TV channel, broadcast or transmitted for everyone to watch at the same time.