Hi,
Unfortunately I missed the one last week, but have seen the other three, including last night's. I have mixed feelings about the format, but am pleased/grateful that Mark has managed to put in so many plugs for glass in all the episodes I have seen.
I have to make an unfavourable comment on one of his pieces of advice given in the second episode about buying cut glass decanters.
Specifically, how to tell when a stopper matches a decanter base ....and if anyone tries it on my stand....they will be politely, but firmly asked to leave

NEVER, NEVER, NEVER turn a stopper in the neck of a decanter so that you can lift it up using only the stopper. Apart from any possible accident that could occur if you omit to give it gentle support below, it is possible that the two pieces (stopper and base) can be locked together - especially if they are unpolished. Then its off to the restorer to get them parted!!
What should you do? Well simple hold the base with one hand and use a finger of the other hand to see if the stopper 'rocks' in the base. If it does it is not the correct one. (Although occasionally there can be a minor 'kick' which can be OK). Yes the number matching is important, but has become less so since it is commonly known, and of course this is an easy thing to change/fake.
The most important thing to do is to note whether or not the two pieces actually match, then, check the fit.
Nigel