If you would like a video preview box to show up before you enter the online services, there is an option in your Zoom settings called "Always show video preview." If this is checked "ON" then every time you enter a meeting, a video preview box will open and give you the choice to turn your video on or off before you enter the meeting. Additionally, you can also turn on the option in your Zoom settings: "Always turn my video off." This means you will always enter the meeting with your video off.