Definitely common in our house! I had all my old videos in a cupboard build into the wall and when I went to clear them out, about 10 had mould. Didn't notice it at first and tried to play one of them - and ruined my old video recorder! I could replace all the others, but this tape is made up from old cine film from the 30s, 40s and 50s so it is irreplacaable. The firm who cleans up the videos does a dvd for you as well so I'm well chuffed.