The exact amount of traffic cannot be calculated, because on the one hand, the traffic volume depends on the quality of the media files and on the other hand it depends on the device. A mobile phone with a slow connection uses less traffic than a computer with a fast connection. Moreover the traffic depends on user behavior: Does a user watch the whole video and scroll through the entire Pageflow?
As a rule of thumb: Per video-minute each user consumes 10 to 15 MB. Audio files equal 0,25 video minutes. Images and text generate relatively small traffic.