I think it depends on the company. Some companies are primarily and longtime DVD producers, and eventually embraced the internet age by opening a website. And many of those websites began as just a catalog/shopping cart for selling their DVDs. And gradually they began selling downloadable/streaming video clips which were usually scenes extracted from their vast DVD collection. So from this type of company, DVD's come first.
OTOH some companies began as internet-only. And they release some DVD's which are just a collection of selected scenes from their pre-existing website collection. From this type of company, website comes first, and probably the website has a much more extensive collection of scenes.

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