John did that guy in your link just drill the hole , fill it with no more nails and insert his threaded rod? Thats what it looks like from here!
I know its all down to personal oppinions in here and IMO id never hand a plasma like that , it looks very very dodgy

(if ive got his description wrong then ill happily stand corrected.)
Sean - take a look through a lot of the posts in this section , there is plenty of advice about hanging plasmas if you want to have a crack at it yourself!
If you get someone in i dare say it you'd be looking at £125 - £150 per day but if you managed to find someone local he /she may be able to do it in half a day for the half the price so probably best to ring round for some quotes.
Be warned though , fitting a plasma screen is more of a specialist thing so some cowboys will try to exploit this fact!
In my opinion , if you know how to use a basic sds hammer drill then there is no reason why you cant have a crack at it yourself!
Jon