I missed part of a program which started already. Is it possible to watch it from the beginning?

Yes, it is possible and it’s easy. While the program is still running, press the ‘Guide’ button on your remote control. The Electronic Program Guide appears and the running program is highlighted. The detail page of the program shows up when you press the ‘OK’ button. Press  ‘OK’ again and you can choose between ‘Watch live’ and ‘Start from the beginning’. Pick ‘Start from the beginning’ and the program will start playing from the beginning.

To watch programs that are entirely in the past: press the ‘Guide’ button and find the program you want (choose a different day using the green button if necessary). Press the ‘OK’ button once and the detail page of the program shows up. On the top right corner you have the choice between ‘Watch now’ and ‘Record’. Press OK to ‘Watch now’ and the requested show will start from the beginning.

And: you can use the REW button to find the beginning of a program, but using the GUIDE is faster.