Unfortunately, the inputs cannot be relabeled. In theory, you could shift inputs around on the source buttons on the 950's remote, but I don't know of a way to re-assign them in this manner and I'd be a little wary of trying it.

Rather than leave you totally out of luck, I'll offer this thought: I switched to an MX-500 remote about a year and a half or so ago, which allows you to create your own labels. In my case, the DVD recorder is connected to Video1 and the label on the main screen is "DVD-R".