Comment by foobar1962

I worked in a broadcast company archive (doing database work). Tapes were often reused. Fragments of previous recordings -- sometimes just a few frames, occasionally many minutes -- may remain at the beginning or end of the tape. AFAIK tapes were never completely erased before recording over top.

I was invloed in a digitisation project, the scanning companies were instructed to process the whole tape in case there were fragments of older programs at the end. A 30 minute tape may have 15 minutes of program, then a period of blank/black, then the remains of an older program for several minutes after that.