paul garret makes good point in a commentcomment that I think deserves its own answer.
If it is a regular thing, some ground rules may make sense: do not talk too long, take open-ended questions offline, do not take calls while attending, and -- maybe -- do not use electronic devices while somebody gives a talk.
Assuming there is a host for this seminar, i.e. the person who sends the invite, talk to them. Ask them to establish a set of rules and enforce them. You can propose a rule regarding your wishes.
