For example, a 1 hour long video lecture has 400 MB size. If it is watched by one user, the bandwidth utilized is 1*400 - 400 MB. For 50 users, it will be 50*400 - 20 GB bandwidth. If 20 users, each watching 10 times, then the bandwidth used is 20*10*400 - 80 GB. Hence, bandwidth usage depends proportionally on the number of viewers and their viewing time.