video processing in matlab

hi, While I am running these lines of code in matlab used in the example file of video processing in sysgen

    load v4_vid_seq
    img.time = [];
    img.signals.dimensions = [128 128];
    img.values = v4_vid_seq;

I get an output in the workspace as shown where v4_vid_seq is a .mat file

Now suppose I need to insert a different video..so in what format I need to store it in the workspace to get the same output.