The
BVWS (British Vintage Wireless Society) (blatent plug
)have released a number of DVD's of this type of material over the years (including the one referred to on YouTube), having had permission from Philips/Mullard to do so. I know as I authored some of the DVD's.
Fascinating and informative these films certainly are, I don't think anything really proprietary/secret is shown - the general principles are largely the same, its the fine details that would be secret. For example temperature/time/heater drive during activation.
TTFN,
Jon