It is obvious that opinion is divided over this issue. Generally the Kissin contribution is considered outstanding by any standards. This is true - he fairly sizzles throughout the concerto then completely ignites for the encores!
Demidenko, on the other hand, has disappointed many purchasers, largely for not delivering the same type of brilliance. This is an easily understood reaction but I am not sure that it is quite fair to Demidenko (or maybe even Chopin!).
My personal view is that Demidenko is essentially deliberately taking a more introverted and reflective view. This is not as immediately appealing as it does not portray such surface glitter as could be achieved. However, I have found it to be perfectly satisfying on its own terms and over repeated viewing. It seems to me to be a viable alternative view - but only providing that you already have a livelier, more regular approach in your collection (and there are many to choose from). I certainly don't think the second concerto would have been capable of this view - but that wasn't tried!
So, best to see this as one obvious winner and one possible alternative view which you may, or may not, share. I think 3 stars would be unfair in view of this summary, hence the 4 stars. Maybe 3 and a half ....?
Further comment - I have found this DVD disc to be so sufficiently rewarding in terms of both musical values and recording values, sound and vision combined, that I have since sold it and replaced it with the Blu-ray version. Significantly, I have not regretted this additional investment as the Blu-ray version brings all the advantages of the expected additional recorded clarity at all levels and would be my primary recommendation.