Depersonalization phenomenon as described in the Pali Canon

The 9 'successive extinctions'( as it is said in A. IX, 31) :
In the step 7 it says "..., the perception ... consciousness is extinguished".

"In him who has entered the 1st absorption, the sensuous perceptions (kāma-saññā) are extinguished.

Having entered the 2nd absorption, thought-conception and discursive thinking (vitakkavicāra, q.v.) are extinguished.

Having entered the 3rd absorption, rapture (pīti, q.v.) is extinguished.

Having entered the 4th absorption, in-and-out breathing (assāsa-passāsa, q.v.) are extinguished.

Having entered the sphere of boundless space (ākāsānañcāyatana), the corporeality perceptions (rūpa-saññā) are extinguished.

Having entered the sphere of boundless consciousness (viññānañcāyatana), the perception of the sphere of boundless space is extinguished.

Having entered the sphere of nothingness (ākiñcaññāyatana), the perception of the sphere of boundless consciousness is extinguished.

Having entered the sphere of neither-perception-nor-non-perception (neva-saññā-nāsaññāyatana) the perception of the sphere of nothingness is extinguished.

Having entered the extinction of perception and feeling (saññāvedayitanirodha) perception and feeling are extinguished."

Since the progress in complex if one likes to follow it just by thought and not just doing it by simply practicing the eightfold path, this might be useful to answer the question: Selves & Not-self The Buddhist Teaching on Anatta

There are also stages of depersonalisation, the first is Stream-Enter where one gains a first glimpse of it and is directed to Nibbana.

In regard of your question:

As a secondary question- could anyone share their personal experience with/knowledge of depersonalization occurring as a result of meditation?

You will not find something satisfying, since:

Repudiating this All, I will describe another,' if questioned on what exactly might be the grounds for his statement, would be unable to explain, and furthermore, would be put to grief. Why? Because it lies beyond range.

And even the Buddha did not share such. The task is done, that's it.

Maybe some of the Verses of there Theragata (the Verses of the Elder Monks) or Therigata (Verses of the Elder Nuns) are useful to get an impression.

It's hard to be sure what he's talking about, because obviously the Pali canon doesn't use the modern definition of DP/DR.

In the video he says a few things to describe what he's talking about:

• That it's "DP/DR"
• That it's very rare (so very rare that it shouldn't be used as a reason for not meditating)
• That whereas enlightenment is liberating and makes your life bigger or fear-free, the "Falling into the Pit of the Void" experience/phenomenon that he's talking is the exact opposite of that
• That it might even be the same (the usual) realization (of emptiness) as enlightenment/liberation, however in these (allegedly rare) cases the person reacts to it differently
• That he (as a teacher) treats it by saying to such a student, "That's good! Now that you know emptiness you can rebuild yourself better than before" and then (like a physiotherapist would with an injured person) forces them to exercise (e.g. to concentrate on positive virtues)
• He uses the word "nihilism"

I suspect that the description in the Pali canon (of derealization if not of depersonalization) might be of bhanga, see for example the descriptions in this answer.

I find it difficult to think of any place in the suttas where the results of meditation are described as pathological -- but one place might be the Vesali Sutta (which might be a description of nihlism).

The video doesn't say so but I wonder whether pathology/disorder might be understood as some imbalance (see for example, Balancing the spiritual faculties).

On the subject of "mindfulness" as a possible antidote, according to modern psychology "feelings of unreality (depersonalization or derealization)" can be among the symptoms of "panic disorder" and "acute stress reaction" ... and (to some extent Westernized) "mindfulness based stress reduction programs" is one of the clinical techniques that psychological therapists use to help to treat that.

Many practitioners experience some kind of "terror". This would be a good sign of advancement in ones development. The Dhamma teaches 'no self' for the development of 'right view'.

When ever personal identity is undermined in some way there is inevitably a sense of threat. When the aggregates-of-clinging are seen as 'not self' this may bring up this sense of threat. Confidence in the Buddha, Dhamma and community of practitioners will steady such a sense.

Fun can be had with this kind of 'terror'. For example walking backwards over a sidewalk kerb, into the camber of a (quiet!) street, with one's eyes closed, so as to deliberately set-up an 'unexpected' shock, could be one way of 'investigating' such a sense of terror in nearly perfect safety. Such a procedure could be repeated as often as required to render this experience as 'nothing special': an improved sense of self confidence may even result.

(As a secondary question -- I'd be happy to read or chat with anyone who could share their personal experience with/knowledge of depersonalization occurring as a result of meditation.)