[James2001]

Might depend on the show, Coronation Street got caught up in a home "exclusive" thing:
tvforum.uk 

Reminds me of the Brookside Lost Weekend video. While it wasn't broadcast, they kept referencing the events of it in the regular show to the point where people who hadn't seen the video had no idea what was going on. At least other home video spin-offs of soaps tend to be pretty much stand alone. Usually they were set up in the main show (though Fiona and Maxine's presence in the Corrie Viva Las Vegas video went against the continuinity of the main show), but they didn't tend to mention the events of the video in the show afterwards, so it didn't matter if you'd seen it or not.