I remember this very fondly too.
The idea was brilliant - it was the late 80's and video cameras were all the rage, but the in joke was that everyone who had one was really bad at using them, so it was a little shaky, you could hear the odd unkind comment from the guy as he was filming it, and you got a load of observational behaviour jokes of a sloBby family.
I remember the son handing out a keyboard, video etc which it turned out he'd nicked from dixons! the home made video idea originally was little 5 minute clips within the smith and jones series (the series which included the head to head sketches a bit like the old wispa ads)...they then developed it for this long special I'd LOVE to have a copy of this, someone must have VHS'd it! (I remember another "home made.." they did where Mel Smith's character (the lodger) lost all his porn as the shed went on fire after a barbecue.
Hard to explain how good this was - it was just class