Hi Jennifer, your computer speakers will have to be picked-up by your microphone if you want attendees to hear these noises. You can combine your microphone with another audio component by enabling stereo-mixing to accomplish this.
Hi June, just like playing a video that is on your computer, playing a video in your web browser will require you to connect your computers audio to the conference call in order for it to be heard.
Downloading the video to your PC and using the GoToMeeting Labs feature to play it is another option but, this feature was released as a test and is not 100% reliable. I'd advise testing your video with it first to make sure it can be played and viewed by an attendee.