That is because it is illegal to sell (and probably import) such copy-protection by-pass boxes in the UK, and has been for many many years (since the '80's).
Given the US millenium digital protection act on digital copying, I am kinda suprised that the analogue equivelent is available still in the US, but lets not worry about that.
As for 'need', there is an interesting word. Want, strong want perhaps..
Still you are allowed to backup your media....for personal use, despite most Videos lasting a long time. There is un-official allowance to move a recording from say a record/DVD to say a tape or mp3 for the car, though you are not supposed to maintain use of both recordings - that should be a 2nd purchase (right, wrong or otherwise if you consider that the copyright is to have a copy not a copy on a particular medium).
All that said http://www.amazon.co.uk/HQ-MACRO-PLUS-Copy-Decoder/dp/B000FDAKY8/ref=sr_1_sc_1?ie=UTF8&qid=1318101469&sr=8-1-spell
There are many (UK) video copy 'stabiliser' boxes that will do the same job as part of their 'stabilisation' process but they may not advertise of declare/promote openly that they will 'accidentally' remove the "Macro-vision" (now called Rovi) feature of these recordings (and DVD's also).
The good ones also allow you to correct colour and contrast as it copies, to restore the recording also.
Such stabilisers are legitimately needed on very old TV's as their video circuits work the same way as VCR's so get affected in exactly the same way.. .hence their pictures need 'stabilising' ;) http://en.wikipedia.org/wiki/Rovi_Corporation
- MacroVision/Rovi protection