Macrovision is the copy protection that is used on most DVDs to prevent you from copying the film to VHS casette. It is also used on pre-recorded VHS casettes, and occasionally on digital TV (e.g. to prevent people from recording pay-per-view events).
There is a way around this. Most DVD players can be hacked or chipped to have Macrovision disabled. You can also buy Macrovision decoders (sometimes nicknamed "bug-blasters" or similar) that plug between the DVD player and the video recorder.
It is also worth noting that some video recorders just ignore Macrovision altogether and will record/copy from protected sources fine. I believe certain Ferguson video recorders can do this.