Oh Piotr... <heavy sigh>... I am just so disappointed with you and this one is even worse.
I AM KIDDING!
You continue to make great videos and even greater music, I always enjoy it even if I don't always post.
A couple of points... the mic is obviously in the way, I'd love to see your playing... you could have placed the mic close it in front of the accordion (to the right in the video), with no loss in quality. About the mic, you don't need a pop filter, unless you talk in to it using "P, B or T" sounds (also known as "plosives") hard.
Why didn't you play the complete song, it was so nice!