There was another TV show I can't remember what it was that pushed out exclusive episodes or material on home video, only for it to air on TV a few months later. There was quite an uproar about it, ironically enough.
That was Coronation Street: The Cruise in 1995, it was sold as an exclusive-to-video episode and ITV then showed it on telly three months later, as you say to much uproar and people appearing on Right to Reply and in the papers asking for their money back. They carried on with these straight-to-video things - for Corrie, Emmerdale and Heartbeat - but after that they would never say they were exclusive to video, but that they wouldn't be shown on TV for X months. And ITV did show most of them in the end, even though they presumably seemed a bit out of date by the time they did.
The Gavin and Stacey thing was an absolute storm in a teacup, the series was delayed by a few weeks so it would finish at Christmas which meant the DVD - which presumably they wanted out for the Christmas market - came out before the series finished, and there was a hoo-haa over the money-grabbing Beeb demanding money to see it first. Which affected about 0.0001% of the audience.
A decade earlier, the second series of Harry Enfield and Chums was rescheduled quite late in the day from autumn 1996 to January 1997, but the VHS release came out for Christmas 1996, so it was renamed "Harry Enfield and Chums 1997" and sold as a preview of the new series. Nobody seemed that bothered about that one, mind.