Shaykh Ṣāliḥ al-Fowzaan (may Allaah preserve him) was asked about women watching TV programs that show male students and/or scholars giving classes. He said:
By Allaah, this is a trial. This issue of TV screens (and monitors), the appearance of men in front of women, and women in front of men, all of this is a calamity. A woman can listen to reminders and classes on the radio where she does not see any picture.
It should be noted that there is differing in this issue, and other scholars have allowed women to look at men, so long as there is no lust or possible fitnah. It has been reported that Shaykh al-Albānī quoted Al-Haafith Ibn al-Qattaan (d.628) saying:
I do not know of any differing over the permissibility of a woman looking at a man's face, so long as she is not looking with desire and there is no chance of fitnah... Similarly, I do not know of any differing about the permissibility of men appearing with their hair, forearms, or calves exposed in the presence of other men, or in the presence of women.
Source: Quoted in a response to the first post mentioned above on sahab.
The response I gave to this question after one of our Kitaab at-Tawḥīd classes was similar to that which is attributed to al-Haafith Ibn al-Qattaan above.