See
http://www.earlytelevision.org/ksd-tv.html
Looking at this TV show schedule there are several 10 minute segments called "Musical Films". Which may be similar to modern day MTV videos. Most likely these are just films showing an orchestra playing their instruments doing a classical piece. I do remember seeing a cartoon (not in 1948, wasn't born yet) of dancing geometric shapes set to jazz music that was probably made around WW2.