^An interesting idea....however what we call themed videos are more based on stories or music videos....another name for this type of video is "machinima"
I do like my themed videos, however I just never have the time to make anything...I remember a site Britannica Dreams had a 1 minute movie challenge based around a single idea or word or theme. Everyone made a 1 minute movie...this kind of setup would probably be something I would get involved with as the time limit means a shorter film and more creativity within a theme. Heck I could even run it. The original was not competitive but for our purposes we could always change that
Here is the original place where I saw it and made a couple of films:
http://www.oneminute.britannicadreams.com/Would anyone else be interested in this type of format?