Re – question 863 above
Q. Thank you – but I learned that when a goy does a melacha for a Yid on Shabbos, the melacha is not forbidden in benefit forever. The Yid can benefit after Shabbos if he waits the amount of time it took to do it.

A. Indeed, when a Gentile does a melocho for you it is only prohibited “Bechdey Sheya’ase” or the amount of time it would take for the work to be done after Shabbos. The reason as Rashi explains on Maseches Shabbos(122a) in regards to bathing on water that was heated on Shabbos by non-Jews, is that by waiting until it could be heated after the end of Shabbos one avoids benefiting from the melocho of the Gentile. (See Shulchan Aruch O.H. 326: 13.)
However in your case, the recording cannot be done after Shabbos, since that is not when the class takes place, therefore, you will always be benefiting from the work that the Gentile did for you on Shabbos.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a