Ha ha, that antiskating video cracked me up ! I actually did follow this very bloke's advice on SL1210 repairs - which are GREAT and highly recommended. But with this antiskating one he "kicked in the fog" - as is the slang expression for such beahaviour around here. Cleaning the records DY style as in one of his other vids is not exactly my cup of tea either...
Blank disk is for setting the antiskating, or more precisely put the total lack or absence of, in setting up self propelled linear tracking arms ONLY, be it air or roller bearing type. These arms, particularly air bearing with next to no friction ( wiring is the limit and !"#$%&/())==?* ( curse outdoing anything in English language ) of linear arms ) are far better spirit levels than anything else, and will tend to skate outwards or inwards if TT is not levelled to the n-th degree. In fact, they are used to level TTs ... This, of course, if the lateral geometry with the linear tracking arm is PERFECT - no visible error across the entire playing surface. Else, there are vectors also affecting "antiskate" - do not try to "fudge" slight geometry error with "leveling" - make it right !
Antiskating is ALWAYS a compromise. The higher VTF required, the more inevitable antiskating errors are pronounced >>>>>>>> linear arms.
At up to say 1.2 gram (12 mN to be exact ) it is kind of OK, above that it starts to rear its ugly head and becomes audible. It depends on the stylus shape, cartridge suspension, tracking error, etc, etc - and can only be adjusted correctly with the aid of a good test record, such as oft cited HiFiNews HFN test record
http://www.vinylengine.com/hfn-002-test-lp.shtml. There is a catch & dillema only you can decide what to do : in order to be able to track the high(er) levels of the modulation at 300 Hz ( which became the standard frequency for tracking purposes ), particularly the highest +18dB track, you will usually have to apply FAR more antiskating. It is needed only for the short durations of peaks, less than 1% of the playing time - but will pull towards outside , skewing the central position of your cantilever towards inside and increase the stylus wear on the right channel side 100 % of the time. My decision is to decrease the antiskate low enough that there is no "morse-code" type of mistracking of the right channel at the highest level cartridge can still play within or slightly above the VTF limits as prescribed by the manufacturer - but do not push for completely clean signal in both channels at the highest level track.
See why I ultimately grew to prefer linear trackers? - NO such compromise involved. Sometimes, you can have your cake and eat it too.