Video editing: extend the final frame on videos to run for extra 30 seconds

I have sixteen short videos that need minor editing, they can be found here: [login to view URL] I need all features of the videos to remain the same, do not change file format, frame size, resolution or length in any way other than the way requested. These are to be used in a research experiment and have been carefully designed. The edit needed is to loop the FINAL FRAME of each video so that the final frame continues for an addition 30 seconds of video time. The final result will be the existing video, with the still shot (last frame) of the 'empty aisle' continuing for 30 seconds. The final frame may be slightly different for each video so cannot be re-used, it must be captured from each video. The final frame will always look something like this though (an empty aisle): [login to view URL] The delivery will be in two stages: 1) the first video edited to the description above to confirm that the process being applied is correct 2) the delivery of the remaining videos once the first one has been approved.