Why is it that every single time they were talking about a DVD Player in the movie they always called it a DVD. Every first rate home entertainment system has to have a DVD. etc…
It bugged me just a little more than when people talk about PIN Numbers (really, you have a Personal Identification Number Number).
Writers like to add little “quirks” and inside jokes to their characters to make them seem more lifelike. Maybe the writer/director/producer knew someone that called it a DVD. FWIW my mom calls it a DVD. She also calls anything from Taco Bell “A Taco Bell.”
There are a few brand names that because of their familiarity to the American Public (I don’t know about other countries) have come to mean the object manufactured:
[ul]
[li]Kleenex: facial tissue[/li][li]Thermos: vacuum bottle[/li][li]BandAid: bandage[/li][/ul]
Not sure what this has to do with the OP, but I thought I’d throw that in. 
In the South every soda is a Coke[sup]TM[/sup].
This reminds me of an ad for some electronics store. Husband, in a fit of electronic-store-buying frenzy, buys several movies on DVD and rushes home. Wife: “We don’t have DVD.”
Yes you do, he’s holding a few of 'em right there. You don’t have a DVD player.
Exactly, so if you have a DVD what the hell do you play in it. It wouldn’t make sense to play a DVD in a DVD.
Another thing that bothered me is when someone offers a little kid “an ice cream.” “An ice cream” usually in reference to something like a popsicle or and ice cream bar etc…
Well how many people say “video” rather than “video player”? Or “video” rather than “video cassette”?
And what about 'phone? It could be gramophone, microphone, etc. But we know it’s telephone because of common sense and common usage.