Well, some new wrinkles there - not the same melody or chords as indicated by the first source, I mean so it would appear to me - if theres a systematic transformation that produces one from the other, Id be interested to know how it works!
I would feel free to stick with the melody in the first source for now - sounds to me more less in line with the
Teija Niku. Those are the only two renditions Ive heard so far and it looks like there are plenty more out there.
Anyway, back to the original question, interesting that Vasilija Radojcic puts in the same key as the original source for Bb instruments. It matters only if there are other parts that will join in, and in that case the thing to do is check those parts to make sure everyone is in the same effective key. If youre on your own, might as well play it as written if you like.
The chords dont look very good, though. Dont take my word for it, I havent really worked on it, but for example the Em in the second line is more like G to me, the change to D in the first line doesnt happen right on 1 as shown (you can see this difference in Zevys example also.) Theres more. If you stick with the music as written, youll be in the same key as the Vasilijia Radojcic video so you can use what you hear without having to mentally transpose.