‘Bandwidth’ refers to the speed of your Internet connection. The higher the speed, the more video data that can be delivered to you per second. The amount of video data determines the size and/or quality of the video picture, so it is desirable to have as much bandwidth available as possible.
Premium service from an ISP (Internet Service Provider) can offer 5 or more Mbps (Megabits per second). Less robust services may only give you 1 – 1.5 Mbps (what I consider ‘medium’ bandwidth). Note that due to local service conditions, your effective speed may be substantially less than the quoted speed.