[Harp-L] Key for this version of "I'm so Lonesome I Could Cry" is ?

[Opus314 .]

I found this video of Chris Bauer playing I'm so Lonesome I Could Cry.

https://www.youtube.com/watch?v=X-H0rz00lFY

and I really like it !!!!

He changes keys/harmonicas later in the tune.

Can any of you guys tell me the initial key and the key he modulates to
later on?

And... where can I get this backing track?

Also any tabs for this great Hank Williams tune?

Finally, I'll be darn'd if I know who Chris Bauer is... probably some
famous player everybody knows but me... but regardless this rendition has
motivated me :-)

Thanks for any help.

PS - I was able to find some of the notes on the C diatonic... crossed to G
I think but I'm not confident in that... and no idea where he modulated
to...