I had problems with Press-It labels, causing read errors on my mp3 dvd-r's.
I established that the labels caused a weight-throw imbalance, which created problems with my DVD-ROM Drive on the PC.
Funny thing was, they played on my m8's PC OK, so I assume it depends on how "tolerant" the read drive is. In view of this, I never tried them on movies.
Since then, I have played safe and stuck to a marker pen.