I found Skype to be the easiest to use with these requirements. I hosted a Jackbox game and was able to share my screen (and game audio), my webcam (albeit in a smaller view than normal), and could see everyone in a gallery view.
This was my first thought as well. I thought it was bad when it just verified that you had used a correct username after attempting to log in, then I kept reading and saw the auto-complete combobox of usernames...