There is a an old video of the first ascent of Quicksilver; I think it included Mask of Death in Nantlle also. It's very good and explains the problems with vagaries of catching the best conditions for Pistyll Rhaeadr.
I'm in Machynlleth and can report that it's been overcast at night of late so frosts are not that severe. Most roadside seepages have yet to show any signs of icing-up.
In reply to Got a job rob: was up there last night. its thin but might go on the right. ther is a gap in the ice about three quarters of the way up but looks do able im gonna try it on a top rope first to see.