As a best practice when adding a speaker who will be speaking during a webcast, you should upload a picture of the speaker with the recommended size of 180 x 180.
This is suggested because, in an audio-only microphone-based webcast, the speaker's photo will display while they are speaking. If no photo is uploaded, the standard silhouette will be displayed instead. For this reason, a photo should be set as the stock image will display by default.
Once a webcast is recorded the image cannot be updated for future playback, the image is set.
While creating the staffer, you will be prompted to choose a file. You may upload a file to the CMS from this link. If you have already had this staffer in a different event in this tenant, their picture may already exist and you can choose to use it.