Unfortunately, being an impoverished artiste as I am and on a shoestring budget I do not have a strong internet service (currently dialup) and cannot easily download stuff on audio and video easily that you are referring to.
I sympathise with this, as you may see from my earlier posts in this thread I was in a similar position. Then I did manage to download the videos (they worked out about 15mb each) but I still can't play youtube videos "live", as it were. Probably a blessing, I only download the occasional video I am particularly interested in.
I did post a written transcript of the two video parts, although of course that isn't the same as hearing the video, if you still can't download the videos.
If, and only IF, Dagar supports his stance with a demonstration that relies on measurable difference in pitch to demonstrate difference in the SAME Sa, then the whole thing is open to the kind of confusions and rightful challenges we have seen in this thread.
My suggestion is offered as an EXEGEGIS (or reconicilation) in a context where I have heard a difference in the SA where both SA's had the same pitch but each was identifiably different enough to invite building different a ragic scale. That difference was due to timbre. Eg, in one we hear the Sa Pa drone with a certain komal Ga and the other a a slightly flatter komal Ga.
I think at the heart of the discrepancy here, is this - Ashish S states the matter clearly re tanpura tuning. (I think Bahauddin Dagar was going to demonstrate this on the tanpura before he was sidetracked - sadly for us and this discussion - by the questioner who rather brusquely told him that wasn't the question he wanted answering).
The two centre strings of the tanpura establish the sa, and the sa of the raga to be performed, which varies in relation to this, is tuned on the fourth string (the kharaj string). The first string, which is usually tuned to pa, ma or ni, is made to coincide with the overtone of the fourth string.
I make no apology for quoting this again, because this is necessary to the point I am making here, that the tanpura tuning demonstrates TWO sas, pitched differently. One the tanpura sa, the other the raga sa, which varies in pitch from the tanpura sa.
The implication from Ustad Bahauddin's video is that the played sa (raga sa) on the been, is not the tanpura sa and varies in a precise way by pitch, and pitch alone. The pitch of the raga sa then is the base for the raga's individual soundscape.
This is at divergence regarding tanpura tuning with your experience you quoted
I have tuned the tamboura and everything is set according to A440, the three C# Sa-s and the G# Pa. Guruji walks in and starts fine tuning the tamboura for the next 10 minutes at the end of which the three C# and the G# are still the very same pitch as I had them!!!!
and to my mind the "two sa" tanpura theory emerges from my blunderings through this topic as rational, more plausible and understandable explanation of how the magician does his trick, than relying on a more vague and undefined theory of how the percieved raga sa is down to "timbre" only. I suggest once the raga sa and the tanpura sa are pitched "correctly" then timbral changes can then
be imposed on this basic tanpura tuning to evoke a particular raga.
We've disagreed on this detail previously, so I don't think we'll be in full accord still
But do have a look at the Ustad Bahauddin videos if you can - even if they don't provide the full solution they give further food for thought - in my mind I have perhaps more and newer questions than before!