The way that the voting works is that between 2010-2015, each country had one set of points to give, averaged from both televote and jury, so technically they could cancel each other out. The exact calculation changed a few time but that's the gist. From 2016 onwards the jury and televote has one set of points each and thus don't directly interact with each other (so, say a 1st in the televote and last in jury would still give the full 12 televote points and vice versa)
Also, no, you cant vote for your own country. You can of course vote for your own country if you live somewhere else so countries with a lot of diaspora (like yes, Poland) are advantaged a decent lot
1. You can't vote for your own country. 2. These years Poland got so many points from UK and Ireland because 'half of the Poland' lived there 3. Check the song by Michał Szpak which you showed - it was last according to jury and 3rd according to all of the tele votes.... That was the biggest the difference ever between tele votes and jury votes.
