I remember being very excited by iTunes and buying a bunch of DRM'd music. Then my tastes changed in a music player and my music buying went downhill fast. After DRM was dropped, I have started to spend more money on music then I did even as a kid.
For some reason DRM'd books do not bother me as much. I am fine being locked into Amazon because I do not collect books and with the exception of reference books, I rarely read a book more than once.
However, dropping $20 on a movie or $30 on a TV series and being locked into a particular vendor really inhibits my spending. When do you think they will let go of the DRM? Is the video DRM so much superior to the music DRM that it is preventing piracy or are they just preventing sales?