That post is dated 2006 and is just about certainly based on the frame and scan rates of the no-longer-in-use-for-broadcast NTSC 3.58 system. Unless you used an old TV (CRT not flatscreen) with an NTSC signal, the results won't be accurate for estimating shutter speeds. The new system may still show valid info for relative speeds of the curtains though. Leitz used a similar method before TV - http://www.skgrimes.com/library/old-...shutter-tester
By "rear curtain" do you mean the first/opening or second/closing curtain? They are not always in the same relative fore-and-aft positions on all cameras.
If you really want fun get a Kiev - metal slats running up and down!
Well I still use an old TV with the digital converter box. Doesn't the box convert the digital signal back to the 525 line, 7875/30 frame system?