So you might see this message on a ITV +1 channel :-
Sorry, for legal reasons we cannot broadcast the service that was shown earlier on ITV1 or Sorry, for legal reasons we cannot broadcast the program that was shown earlier on ITV1
If this message appears on some adverts, how I understand it is that channels are allowed to use up to 15% of their broadcast time, that’s 9 minutes per hour, on showing commercials. They can go up to 12 minutes in one hour as long as they take the extra 3 minutes away from a different hour of the day. They might want to put the full 12 minutes in a high-rating programme, and take the 3 minutes away from something which isn’t so popular. If this happens then ITV + whatever channel goes over the 15% ratio on the hours which do remain. The only way to put that right is to blank out some adverts to restore the balance.
If this is on a while film or program then a lot of ITV’s content isn’t licenced for the timeshifted channel, i.e. the +1. They only have the rights to show it once, and a timeshifted channel is counted as a repeat showing. For some stuff if they wanted to show it again it would cost them quite a lot.