Young Catherine was the series in which I "discovered" Mark. So it holds a very dear place in my heart and in my VHS tape collection (I have an original version that my SIL taped for me back in '91 when it originally aired on TNT!)
But I do know that there are versions of Young Catherine out there for sale on Ebay and other places and some of the prices are very steep. The cheaper priced versions are usually the edited versions (look for time length), which as I understand it, there is a lot of Mark's role left on the cutting room floor. How could they?
So be wary when shopping around for this particular series!