Q. If someone attends a shiur by Zoom and the others can see him attending, is he allowed to leave early? Could this be considered as abandoning the mitzva of 'Berov Am Hadras Melech" (a mitzva should be done by many) and we hold that Ein Maavirin al Hamitzvos or one should not avoid or abandon a mitzva?
A. Poskim debate whether it is permitted to abandon a Bris Milah to attend a Chupa and the opposite. (Machane Yisroel 38). Igros Moshe (O.H. 2: 95) maintains that one should not abandon a Sheva Brochos to attend a Bris Mila since at the former he complies with the mitzva of being Mesameach Chosson Vekalo or giving joy to newlyweds.
Chashukei Chemed (Yuma 70) relates that someone (not an invited guest) approached Horav S.Z, Auerbach zt'l at a chupa, to ask a shailah. After answering the Rov told him, that he is not allowed to leave until after the ceremony, ends following the ruling above.
Horav Shlomo Miller’s Shlit’a opinion is that in need one can leave the Zoom shiur.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a