Is it the function that enables you to watch a movie from its beginning while the movie is still being recorded?
Thanks

Yes, that's what it is. Depending on the recorder, it can also be called "Chase Play".

Thanks s lot.

Depends on the brand. For Panasonic, "chase-play" is the term used for watching a show while it is still in the process of recording. "Time-slip" is entirely different and is the name given to the feature that allows you to make big jumps forward or backward in a recording by specifying any number of minutes.

On Toshiba models, they refer to the feature as the "Chase Play" function but tell you that to engage it, you press the "Timeslip" button on the remote. Typical owners manual.

The other function is called instant skip/instant replay. You set a specific length of time(default is 30 seconds which is handy) and then each press of the button moves you forward or back by that amount.