There is a great book on these subjects called "Free Culture." Believe it or not, if a company wanted to go after you for using their cards in a video, they potentially could. They could argue that their copyrighted artwork (the cards) is protected and would require their permission in order to be filmed. (This is why TV and Movie companies have divisions devoted solely to "permissions." Before anyone gets up, I want to be clear that I am not saying this is a good thing, or that the company would be "right" but the law now recognizes this is a somewhat valid claim.While most of us would consider it ridiculous, anyone with a couple hundred bucks can file a law suit.
Having said that, I think any magic company which sold cards would have a PR nightmare on their hands if they did sue.
Grab the book. It's a fascinating read.
Brad
p.s. The fact that you asked is great. It shows you care about other people's property and ideas.